Cold Water Aquariums

Please welcome back Frank Indiviglio for another article.

Today I’d like to introduce you to the maintenance of cold water aquariums, a fascinating but often overlooked branch of aquarium keeping focusing on marine and freshwater fishes and invertebrates from temperate regions.

Exotics Close to Home
Please don’t be misled into equating exotic and interesting creatures with “far-off, tropical places”. Shorelines, ponds, tidal pools and rivers throughout the world’s temperate regions (with the exception of extreme s. Florida, the entire USA is in the temperate zone) yield animals of unimaginable variety and interest. While it is true that many of the most spectacularly colored fishes are found in the warmer parts of the world (their bright colors likely help males and females of the same species recognize each other among the great diversity of similar species in the tropics), breeding males of many temperate fish species, i.e. the sunfishes, do rival those of their tropical counterparts.

Why keep Temperate Fishes and Invertebrates?
Animals from temperate areas offer many advantages to aquarists who live in the USA. Often, our normal seasonal rhythms of temperature and light fluctuation are sufficient to encourage such creatures to exhibit natural behaviors, and even to breed. Also, it is often easier for us to provide a wider range of foods and a more natural environment for them than we can for creatures from faraway places. In some cases, where legal, we may even be able to collect and keep native fishes and invertebrates.

Creating Natural Habitats
If you live near a body of water, try to observe firsthand the environments and habits of a variety of aquatic creatures. You might consider modeling your aquarium after a particular habitat -- a tide pool, a weedy, fresh-water pond, or a river bed, for example. Take note of the local substrates, rocks and other natural items and purchase similar ones when setting up your tank prod (collecting natural substrates is risky, due to the possibility of mineral, pesticide or other chemical leaching).

Heat
Cold water aquariums are maintained in a similar fashion to tropical aquariums, but we must consider the effects of heat. Many animals from temperate regions are very sensitive to rising water temperatures and to the lower oxygen levels that accompany them. You may, therefore, need to install a chiller to moderate temperatures during the summertime.

Species to Consider
Some of the animals that I have maintained with success in cold water aquariums, and which I plan to cover in future additions to this article, include American eels, fifteen-spined sticklebacks, pygmy and other sunfishes, mantis shrimp, sea stars, Chinese sailfin suckers, weather fish, horseshoe crabs, blue claw crabs, bullheads and madtoms, white clouds, various snails, crayfish and shrimp, giant water bugs and other aquatic insects and many others.

I’ll now give a quick overview of two unusual animals – the oyster toadfish and the spider crab - which are easily maintained in unheated marine aquariums. I’ll cover their husbandry in detail in future articles.

Oyster Toadfish, Opansus tau
This unusual marine fish, ranging down the Eastern Seaboard from Maine to Cuba, seems to cross the line between fish and amphibian – its face even resembles that of a toad. In addition, toadfishes produce sounds audible above the water and certain Asian species can travel overland for considerable distances.

Oyster toadfishes will become quite tame in captivity, and, given a tank of 55 gallons or so, may well breed. Males are ferocious guardians of their eggs, and have been known to stay with nests that are exposed at low tide.

Oyster toadfishes have survived for 15 years in captivity, and will accept nearly any meat-based frozen or pelleted food as well as live shrimp, small fishes and worms. They learn to associate their owners with food, but will bite when handled, and the spines that can inflict painful wounds.

Atlantic Spider Crab, Libinia emarginata
Spider crabs, common yet fascinating if you take the time to know them, are members of a family which includes the Japanese spider crab. With legs spanning 8 feet, these giants awed me when first I observed a large group in a pubic aquarium in Osaka, Japan. American aquariums now exhibit them as well - trust me, they are well worth the trip.

The Atlantic spider crab is a valuable aquarium scavenger, and, using its tiny pointed claws to probe into nooks and crannies, misses little. Younger animals have the endearing habit of jamming algae and vegetation into the crevices of their shells, taking on the appearance of a "walking plant". They will also nibble at this portable garden from time to time. I have found that they forgo this habit when they reach a carapace size of about 3 inches, although I have yet to discover why.

Spider crabs rarely bother tank-mates and readily consume fish flakes, pellets, blackworms, frozen food fish foods, algae and green leafy vegetables.

In the next installment of this article I’ll write about temperate, fresh water animals that are readily available in the pet trade. Until then, please write in with your questions and comments. Thanks. Until next time, Frank.

Information on the natural history of the oyster toadfish, along with a photo, is available at:
http://fishbase.mnhn.fr/Summary/SpeciesSummary.php?id=3069&lang=Portuguese

Oyster Toadfish courtesy of NASA: http://mediaarchive.ksc.nasa.gov/detail.cfm?mediaid=2656

Thanks Frank

Until Next Time,

Dave

Carnival Fish Part 1

Carnival Fish Part 1: Goldfish

It is the time of year when carnivals and fairs pop up across the land, with games and rides and fun for all (well the kids anyway). What that brings to mind here at TFP are all the unsuspecting parents who have suddenly become the proud new owners of a pet fish that their kids have won as prizes in these games, and need to know how to take care of them. Every year we sell thousands of fish to carnivals as game prizes, and then find many people who need help with their new “prizes” after they get them home.

Goldfish and Betta fish are the most commonly found in these games, so this carnival fish blog will give some basic information about the care of these fish. Part 1 will be about goldfish information and care.

The practice of keeping goldfish (Carassius auratus) dates back to as early as 970A.D. when domesticated fish keeping began in ancient China. Farmers would impound carp as food fish, these carp where silver grey fish, like the wild carp found today. A genetic mutation in some of the carp gave them a yellowish gold color. The farmers would then selectively breed these colored carp, over time this selective breeding lead to what we now know as the modern goldfish. As the popularity of these fish grew, and they spread out from China, selective breeding of various mutations in the species has given rise to many different types of goldfish over the centuries. These different types of goldfish include the Oranda, Ryukin, Shubunkin, Comet, Lion head, Bubble eye and more. Goldfish are seen as good luck symbols in many oriental cultures and some breeds even have religious roots; the Celestial Eye goldfish were bred because monks believed their eyes looked towards the heavens.

Goldfish are peaceful fish that do well with other breeds of goldfish or other cold water fish. There are little to no issues with aggression, aside from the odd individual or “nippier” variety. It is not recommended to mix goldfish with tropical fish (tetras, guppies, etc) due to differences in water quality and temperature preferences. Goldfish prefer aquarium water temperatures from 60 – 74 degrees. Goldfish are commonly kept in outdoor ponds that will reach freezing temperatures in winter, provided it can not freeze solid, and a floating heater is used to insure constant gas exchange. Goldfish will tolerate a wide range of pH values, from 6.0 to 8.0, so long as conditions are stable.

Most types of goldfish will reach a maximum length of 6”- 8”, Comet and Shubunkin Goldfish can reach 12” or more. Goldfish can live up to 20 years given a proper diet and water conditions; there have been recorded accounts of goldfish living into their 40’s

Goldfish are easy to feed as the will accept virtually any types of fish food. Flakes or pellet formulas especially for goldfish are best. Avoid meaty foods, goldfish have a high vegetable requirement. Vegetable matter like algae sheets, cucumbers, or peas can be supplemented into the goldfish’s diet to help maintain optimal health.

Goldfish tend to be messy fish, with a big appetite, which leads to large amounts of waste. As a result monitoring goldfish’s water conditions is very important. It is not recommended to keep goldfish in unfiltered bowls, although it is possible if frequent (usually bi-weekly) water changes are consistently done and the water remains aerated. Live plants can be used, although they will usually end up eaten as the fish get bigger. The best environment for goldfish is an under stocked aquarium with ample filtration and regular maintenance.

I hope that this has helped all you new goldfish owners out there, or even peaked the interest of anyone that is considering keeping goldfish.

Until next blog

Dave

The Octopus – General Natural History Notes & the Care of the Common Tropical Octopus, Octopus cyaneus, In Captivity

Please welcome back Frank Indiviglio with another excellent article.

With their sharp eyesight, inquisitive personalities and large brains, octopuses seem far removed from their relatives - the 100, 000 or so species of clams, scallops, slugs, snails and other creatures that make up the Phylum Mollusca (the Mollusks). Over 700 types of octopus, squid, cuttlefish and chambered nautilus are known, with odd deep sea forms being discovered each year.

Octopuses have much going for and against them as pets. They are, without a doubt, the most intelligent of the invertebrates, and often seem to rival much more “advanced” creatures in brain power. Able to distinguish and associate various shapes with a food reward, some have even learned to unscrew glass jars to obtain food. In one laboratory, cameras revealed that an octopus was leaving its aquarium each night to prey upon crabs held in a neighboring tank. Each morning, the octopus was found back in his own aquarium, having crossed several feet of dry shelf space in his nocturnal travels! One that I kept would, according to my grandmother, “watch her” as she prepared dinner (octopus see very well, and notice movement outside their aquariums). Unnerved by the thought of our pet witnessing the demise of his relatives, she would cover the aquarium with a towel on those days when she cooked octopus or squid for dinner!

On the down side, however, all species studied are quite short-lived (2 years at most) – quite odd considering their complex lifestyles. Males generally expire right after mating, and females survive only long enough to see their eggs through hatching.

The species most often seen in the pet trade is the common tropical octopus, Octopus cyaneus (please note that there is a good deal of confusion as to the identification of this species). Growing to a maximum length of 12 inches, it does well if provided excellent water quality (manage it as you would a delicate reef fish) and a secure retreat in which to hide. Octopuses absolutely need to hide and are intolerant of disturbance (although once acclimated many will become quite bold at feeding time). It is also important to avoid suddenly putting on a light if the room in which the aquarium sits is dark. When disturbed, octopuses release a dark-colored ink (sepia), which can be toxic to the animal in close quarters.

Bear in mind that octopuses consume large amounts of food and produce copious waste products – good filtration, frequent water quality tests and water changes are vital if you are to keep them successfully. Give your octopus the largest aquarium possible (this will help with water quality and in reducing stress on the animal) and be sure the lid is weighed down or otherwise fastened. The common tropical octopus does well at temperatures of 76-78 F. As most species are nocturnal, you should equip the aquarium with a bulb designed for nighttime viewing so as to be able to observe your pet without disturbing it.

Most octopus favor crabs, shrimp, clams, scallops, mussels and other shellfish, but usually take fish as well. Seafood markets are useful sources of food for your pet – as we know little of their nutritional requirements, I suggest providing as much dietary variety as possible. The wide range of frozen marine foods now available will provide you with a great many options as well.

Other species sometimes offered for sale include the red or pygmy octopus, O. bocki, which is highly nocturnal, and the common octopus, O. vulgaris. As the common octopus occupies a range spanning the Mediterranean, the Sea of Japan and the Eastern Atlantic, it is likely a fairly hardy creature. However, with a leg-span approaching 3 feet, it is too large for most home aquariums.

It is important to remember that all octopuses, even very small ones, can inflict painful bites with their sharp, parrot-like beaks, and that they can never be considered “tame” enough to handle. Most if not all produce venom in order to subdue their prey, and even venoms not shown to be dangerous to people can cause severe or even fatal reactions in particularly sensitive individuals. Amazingly, the tiny the blue-ringed octopus, Hapalochlaena maculosa, quite capable of killing a human with one bite, is sometimes offered for sale. Learn to recognize this species and avoid it at all costs.

Breeding octopuses in captivity is difficult, as is raising the young. Recent research at the Spanish Institute of Oceanography indicated that dietary factors, especially the absence of fatty acids such as DHA and EPA, are responsible for high mortalities among those that do hatch in aquariums. Enriched brine shrimp have been used with some success, but more variety is likely needed. I would experiment with various species of marine shrimp, worms, plankton and tiny marine creatures seined from eel grass beds and other marine habitats (check the legality of collecting before doing so).

Octopus husbandry is in need of much attention by serious hobbyists. These fascinating, complex creatures are impacted by habitat loss and collection for the food, bait and pet trade. Breeding them in captivity will certainly take pressure off wild populations and help in understanding what they need to survive in the wild.

Please write in with your own thoughts and questions. Thanks…until next time, Frank.

You can see photos of hatchling octopuses and read about a captive breeding effort at:http://www.bbc.co.uk/norfolk/your/a-z_norfolk/a-z_octopus.shtml

Understanding Marine and Freshwater Fish Behavior – nocturnal and diurnal activity

Please welcome back Frank Indiviglio with another interesting article.



Studying fish behavior is both a fascinating and very practical endeavor for the fish keeper. In addition to opening one’s eyes to the amazing diversity of fish lifestyles and behavioral adaptations, research concerning your pets’ natural behaviors will also lead to much greater success in keeping and breeding them.

The primary motivation behind animal behavior is survival - breeding, finding a suitable environment, obtaining food and avoiding predators (yes, human behavior often seems to break this rule!). Of course, even the best-designed aquarium is a poor mimic of nature, and so captive fishes must modify their behaviors – sometimes so much so that the actual purpose or function of what the fishes are doing will be lost on us. However, with experience, you should be able to see the relationship that the captive behavior has to its natural counterpart.

A wonderful aspect of the study of fish behavior is that it will provide a lifetime of surprises – there is far too much for any one person to know, and new facts emerge, quite literally, on a daily basis. With careful observation and research, you may well be able to discover something new. Today I will focus on just one facet of behavior – the time at which fishes are active, and how this affects their welfare in the aquarium.

When selecting fishes for your aquarium, it is important to consider whether they are diurnal (active by day), nocturnal (active by night) or crepuscular (active in the dim light of evening and early morning). This will affect both your enjoyment of your pets and the composition of species that you might wish to include in the aquarium.

Nocturnal fishes such as the fire eel, Mastacembelus eyrthrotaenia, and other freshwater eels, need a place to hide during the daytime. If denied this, they may become stressed and will languish in captivity. However, eels, catfishes and other species that barely move by day change radically at night, and may engage in a surprising degree of activity. These nighttime wanderings may disturb diurnal fishes and prevent them from resting properly, thereby impairing their health.

Unlike the always “ready-to eat” oscar, Astronotus ocellatus, and other Cichlids, nocturnal fishes often appear placid by day and morph into quite aggressive predators only as night falls. For example, octopuses, snowflake moray eels, Echidna nebulous, and similar species are usually quite content to spend the day secluded in a favorite retreat – easily tricking the novice into believing that they are compatible with their tank-mates. At nighttime, however, they undergo quite a change, and will quickly devour smaller neighbors.

Many diurnal fishes, such as the princess parrot fish, Scarus taeniopterus, and related species, swim about actively in daylight but secrete themselves within caves at night. Again, if you see them only during the day, you may miss such points and fail to provide for their needs (shelter-sleeping species become stressed if forced to remain in the open at night).

Please bear in mind also that many nocturnal fishes will not feed during the day. Some, including most catfishes and moray eels, will forego their nocturnal habits once they adjust to captivity. Many, however, (i.e. the fossil catfish, Heteropneustes fossilis) remain strictly nocturnal even after years in captivity, and must be fed at night if they are to thrive.

Just as nocturnal species may unsettle diurnal fishes at night, actively swimming fish (by day or night) may stress species that are largely sessile (fish which move about only occasionally). Most typical "sit and wait predators," such as the various anglerfishes, will be greatly disturbed if forced to remain in close proximity to vigorous, mobile species (also, bottom-feeding predators usually do not obtain enough food when kept with surface-feeding fishes).

The best way to observe nocturnal fishes, and to see how diurnal fishes behave at night, is by utilizing a bulb designed specifically for nighttime aquarium viewing. Be sure to invest in such bulbs, as they will open up an entirely new world of fascinating observations and learning opportunities for you. If you plan to focus on nocturnal fishes, you may wish to consider a complete reverse light cycle, in the manner of zoo exhibits for nocturnal creatures. If a dimly lit room is available, you can leave the night-viewing bulbs on during the day, and give the fishes their “daytime” at night. This may give you more time to observe your nocturnal fishes – unless, of course, you are yourself “nocturnal”! I have been able to learn a great deal about a number of animals, both at home and while working at zoos, in this manner. Be sure to research your fishes’ natural history so that you can provide a day/night cycle of the proper length.

I’ll explore other aspects of fish behavior in future articles – until then, please write in with your observations and questions. Thanks, Frank.

An interesting article concerning the effect of light on fish activity is posted at:http://www2.hawaii.edu/~delbeek/delb12.html

Thanks Frank,

Until Next Time,

Dave

Teach Your Goldfish To Do Tricks With the R2 Fish School

Ok, I thought I would blog about this new product we're getting in at That Fish Place: as it's popping up all over the place lately.



The R2 Fish School from the folks at R2 Solutions company dispels the myth that goldfish, and apparently any smaller sized fish, have 2-second memories by teaching them how to perform a variety of tricks. As wild as it seems, the R2 Fish School is loaded with press showing goldfish in action.



For all of you myth busters out there, the system works by simple positive reinforcement, but it's truly hilarious to watch your fish, literally, swim through hoops. Each R2 Fish School is packed with "athletic gear" to get your fish punting a football through goal posts, scoring a soccer ball in a goal, swimming the slalom, going through tunnels or doing the limbo. The Fish School "arena" fits into tanks as small as five gallons, and parts of it can be used separately in a smaller fish bowl. An instructional DVD is included so you can get your fish into training fast.







Great for kids, or even those adults who are always looking for something else to compete at (Goldfish Fantasy League or Extreme Goldfish Tricks on ESPN2), The R2 Fish School looks like an interesting product. Let me know if anyone has any cool fish training stories to tell!


Until Next Time,

Dave

Pond Health Tip: Using Salt

Pond Health Tip: Using Salt

One of the easiest things that you can do to help promote the health of the fish in your pond is using Salt. Whether you have a small pool of Goldfish, or a large Koi Pond, using salt as part of your maintenance regiment is a simple, safe and inexpensive product that can greatly benefit your fish’s health.

During times of stress, whether from parasites, pathogenic bacteria, or poor water quality, fish can struggle to maintain proper electrolyte balance in their bodies. Fish use special cells in their gills, called chloride cells, to absorb electrolytes from the surrounding water. The absorbed electrolytes play an important role in a fish’s ability to intake oxygen, and release Carbon Dioxide and Ammonium through their gill membranes. When a fish’s natural ability to maintain its electrolyte balance is reduced, they can suffer from a condition known as “Osmotic Shock”. Fish suffering from osmotic shock have trouble absorbing oxygen, and in poor water conditions are at high risk of perishing from nitrite toxicity. Keeping a therapeutic level of salt in your pond will help maintain your fish’s electrolyte balance, and help prevent Osmotic shock, and reduce the stress of elevated nitrites in new ponds, or poor conditions. Another benefit of using salt is that salt will also promote a heavy slime coat on your fish. Your fishes slime coat is its first line of defense of attack from parasites and disease. Proper gill function and slime coat are key to a fishes over all immune system and health.

Salt can be used for several purposes in maintaining your fish’s health. As I have already discussed, you can use salt at a low maintenance level for an indefinite period of time, how much salt can safely be used depends upon your pond. You need to be careful with the amount of salt that you use in your pond, especially when using salt in ponds with live plants. At Higher concentrations, salt can have negative affects on plant life. You need to be sure of your pond volume; this will allow you to accurately calculate your salt dosage requirement. For ponds that have live plants you should keep a maintenance level of salt between .05% - .1%. For ponds with fish only, you can maintain a maintenance level between .1% -.2%, these concentrations are safe to use all the time.

Salt is also a highly effective treatment against common parasites found in ponds, as well as nitrite toxicity. If you do not have plants in your pond, you can use an elevated therapeutic level of .2%-.4% for 2 to 4 weeks, this will reduce the stress of parasitic attack on the fish, limit the parasites ability to reproduce, and even kill many of the parasites. If you want to use a therapeutic level of salt, but you have plants, you can remove your plants temporarily into a kiddy pool, and then treat your pond. After conditions have improved simply perform a water change to get the salt concentration back below .1% and then reintroduce the plants.
Salt can also be used as a short term bath when severe parasite infestation or bacterial infection has reached advanced stages. You can catch your fish, and place them into a high concentration of salt to rapidly kill and remove parasites from the fish. Bath concentrations of salt should be 2%; the fish can be dipped for up to 15 minutes, depending upon the behavior of the fish, and its reaction to the salt bath. If the fish is not handling the salt bath well, or is having trouble breathing, remove immediately.

What kind of salt do you use? Non Iodized table salt (sodium chloride) can be used, but a better choice is a salt that is made from evaporated sea salt, or a synthetic equivalent. While sodium chloride is the major componet in seawater, there are a number of other minerals in seawater that fish can use to maintain electrolyte levels, such as calcium, magnesium and potassium. Brand name salts such as Aquarium Pharmacueticals Pond Salt, and
Pondmaster Pond Salt by Supreme, are evaporated sea salts.

One last thing to remember when using salt in your pond is that salt does not evaporate, so it never leaves the pond. Do not add more salt when you add water to your pond that has evaporated. The only time you need to add more salt is when you have physically removed water from your pond, like from a water change, or a severe rainstorm that caused the pond to overflow. You should always test your salt level before making any adjustments.

I hope that this has helped answer some questions about using salt in your pond

Until next blog,

Dave

Species Profile: Pygmy Angels

Welcome back Mellisa Leiter, one of the Marine Biologist who works in our fish room here at TFP. Mellisa has written an article about one of the coolest little saltwater fish around, the Pygmy Angel. I hope you enjoy!



Pygmy Angelfish

Pygmy angelfish are fairly small, yet bright and colorful. They are generally not-specific feeders and usually accept most prepared food offered to them. They should be offered frozen foods like Mysis Shrimp, Formula 1, Formula 2, and Clams. They should also be offered flakes, pellets, and a regular supply of algae to round out their diet. Pygmy Angelfish typically do well in an established aquarium, 55 gallons or larger. Some acceptable tankmates include damsels, clownfish, tangs, gobies, blennies, and wrasses. As with their larger Angelfish cousins, careful consideration needs to be taken when attempting to keep more than one Pygmy Angel in the same tank. Two Pygmy Angels of the same species or very similar coloration should not be housed together, they will be very aggressive towards each other. If you want to attempt to keep two different species of Pygmy Angels together, your best bet is with species of different coloration. While there is no guarantee that these feisty little fish will coexist in your aquarium, you can increase your odds of them getting along in a few ways. First, the bigger the tank the better; 55 gal tank or larger. Second, make sure that there is plenty of live rock with lots of hiding places, this will allow the fish to establish their own territory. You can also reduce aggression by adding the fish at the same time, this way no territory has been established by older residents. Pygmy Angelfish are generally “reef safe” but may nip at the occasional polyp from time to time. I would not recommend Pygmy Angels for reef aquariums with Acropora, or other SPS corals for this reason. Their max size ranges from 3-6 inches for most species.

One of the most popular Pygmy angelfish would be the Coral Beauty (Cenropyge bispinosus). Their colors range from a deep purple to shades of orange. They stay fairly small (3-4”) and can be housed in tanks as small as 30 gallons. Coral Beauty's are usually "reef safe" but may nip on polyps as well as the slime coat on other corals. The Coral Beauty is very hardy once acclimated into a well established tank with plenty of liverock.

Another hardy Pygmy angelfish that does well in an established tank is the Flame Angel (Centropyge loricula). Their colors are a vivid red with black lines. The amount of black varies. Flame Angelfish do not have different juvenile to adult coloration's so be sure to pick the stripe pattern that you like since it won't change. Flame Pygmy angelfish tend to be more peaceful than some of the other pygmy angelfish. Flame Pygmy Angelfish are usually "reef safe" but may eat polyps or clam mantles.

One of the smaller pygmy angelfish that is also hardy is the Cherub Pygmy Angelfish (Centropyge argi) . Cherub Pygmy angelfish is a purplish blue with a splash of orange around its face. They reach a max size of 2-3 inches. Cherub Pygmy angelfish may be shy any first, but don't let their small size full you. These little angels have attitudes and will defend their home at all cost. They are generally "reef safe" but may pick at the occasional polyp.

One of the larger Pygmy angelfish would be the Keyhole Pygmy Angelfish (Centropyge tibicen). They can reach a max size between 7-8 inches. Keyhole Angelfish are not as colorful as many of the other angelfish. They are mostly dark blue to black with the lower portion of the anal fin bright yellow and an oval white area on both sides of their body. Keyhole Angelfish do not tend to ship as well as some of the other angelfish but once properly acclimated they are usually pretty hardy.

One of my favorite pygmy angel is the Lemonpeel Pygmy Angelfish (Centropyge flavissimus). They are bright yellow with blue trim around both eyes and gill covers. Lemonpeels are generally shy and need lots of places to hide to feel safe. Once acclimated they usually become more social. Lemonpeel angels are more likely than some of the other pygmy angelfish to pick at LPS corals and clam mantles.

One of the more aggressive pygmy angelfish is the Eibli Angelfish (Centropyge eibli). Eibli Angelfish have a silver gray body with orange stripes, black tail rimmed in blue, and a hint of orange around the eyes and belly. These angels adapt fairly well to aquarium life if given an established tank with lots of macroalgae to graze on. Eibli Angelfish are usually "reef safe" but may nip on the occasional polyp or clam mantle.

While there are many pygmy angelfish that do well in aquariums there are some species that are gorgeous but are a challenge for even the experienced aquarist. The Potter's angelfish (Centropyge potteri) and Golden Angelfish (Centropyge aurantia) fall under this category. Potters angelfish are bright orange with blue gray scribbled lines and blue trim. Golden Angelfish are a burnt orange color with vertical yellow stripes. These angelfish tend to be very shy and reclusive and do not readily accept prepared food.

I hope you enjoyed Mellissa's article.

Until next blog,

Dave

Mudskippers – blurring the line between amphibian and fish

Please welcome back Frank Indiviglio to That Fish Blog.

Those with an interest in unique aquarium fishes need look no further than the mudskipper. These odd little creatures seem to straddle the line between fishes and amphibians, leaving the water for long periods of time to chase insects across mudflats and even climbing up onto tree trunks.

Mudskippers, the largest species of which reach a length of 12 inches, inhabit tidal flats, river mouths and mangrove swamps in East Africa, Southeast Asia, Australia, and along the Red Sea.

The mudskippers are unusual in having highly modified pectoral, pelvic and anal fins that enable them to move about quite well on land - they can even leap (“skip”) about very rapidly. In addition, the fused pectoral fins form a suction disc that allows these little acrobats to climb up onto mangrove roots and tree trunks. The eyes are situated at the top of the head and are, for a fish, quite movable.

Gill covers tightly seal the gill chambers, and water stored there keeps the gills moist and provides oxygen to the fish as it scuttles about on land. Mudskippers also absorb moisture from the damp mud upon which they usually travel when out of water. Although it is tempting to think of mudskippers as representing an early stage in the development of amphibians, the creature that gave rise to frogs and salamanders was more like the Australian lungfish, Neoceratodus fosteri, in appearance and in its method of breathing (utilizing primitive lungs).

The most commonly available mudskipper in the pet trade is Periopthalmus barbarus, a fairly hardy species that reaches a length of 6 inches. Like all mudskippers, it hails from brackish water areas.

Mudskippers are fairly tolerant in their salinity requirements, and will do well under typical brackish water aquarium conditions (salinity of 1.005-1.015) and temperatures of 75 - 80F. They require a "beach" area, which can be a separate, drainable plastic container within the main aquarium or designed as small islands fashioned from non-toxic tree roots, coral heads and rocks. The popular “aqua-terrariums” now on the market make excellent mudskipper homes as well. Remember to keep the water shallow, or to provide easy access to land, as they are poor swimmers (not something you usually worry about when keeping fish!).

Most mudskippers do well in captivity if provided with a suitable habitat. Males, however - distinguished by their large dorsal fins and bright colors - are very territorial, and dominant specimens will make life miserable for others, so plan your group and space accordingly.

Although they prey upon live invertebrates such as crabs and insects in the wild, mudskippers adjust well to frozen foods such as prawn and clams. I also provide a vegetable-based frozen food from time to time, and find they accept this readily as well. Their food should be placed on land, as most species will not feed while submerged. Mudskippers are especially fond of live crickets, small shrimp and other such foods, and these should form a large portion of their diet. Their acrobatics when chasing live food – they often flip over in their excitement - never fail to delight me.

Brackish water community tanks containing mudskippers and fiddler crabs make fascinating exhibits. The interactions between the crabs and mudskippers (assuming they are properly matched in size!) go on all day long. If you establish a deep water area (mudskippers will do okay as long as they can exit the water easily) you can add such fascinating fishes as four-eyed fish, Anableps spp., scats, Scatophagus argus and rubrifus, monos, Monodactylus argenteus, and, of course, the amazing archer fish, Toxotes chatareus. In fact, archer fish are at their best in an aquarium containing a land area because in such they can show off their incredible ability to knock crickets from land into water. Somehow compensating for the refraction of light through water, archerfish eject streams of water at insects (best observed by placing crickets on branches positioned over the water’s surface), hitting them unerringly and thus securing a meal. They will also aim water at your eye movements, so be careful!
I’ll cover the creation of such aquariums in future articles. Until then, please share your observations and write in with your questions. Thanks, Frank.

For more information on establishing aquariums for brackish water fish, please see the article Brackish Water Basics, posted on on February 26, 2008:

Blind Cave Fish: Their Discovery, Initial Collection and Care - Part 2

Click here to read the first part of Blind Cave Fish

Blind cave fish navigate entirely through the use of the lateral line – a system of sensory organs possessed by all fish but, it seems, very highly developed in this species. The movement of water (caused by currents or the fishes’ own swimming) bouncing off objects is sensed and used to guide the fish in their travels. I am tempted to compare the process to echo-location in bats, or the use of electricity by the elephant nose fish, Gnathonemus petersi, but it is, of course, quite distinct. If you have an opportunity, observe how well cave fish can move about – in an exhibit at the NY Aquarium they speed through a series of glass barriers unerringly. Individuals introduced to new exhibits may “crash” on occasion, so there may be some learning involved as well.

They are also amazingly adept at locating food – a school I kept at the Prospect Park Zoo in NYC hit food dropped on the water’s surface as quickly as do most sighted fish. In fact, blind cave fish do quite well in aquariums housing other fish species.

Recently (January, 2008) it was discovered that young blind cave fish can detect light via unique compounds in the brain’s pineal gland (the embryos begin to develop eyes, but these degenerate rapidly). This ability declines with age.

In contrast to most cave-adapted fish - which require cold, hard water if they are to thrive - blind cave fish are quite undemanding pets. In fact, they do best at 78-82 F, as their native waters are quite warm. If kept alone, slightly hard water should be provided, but they adapt easily to conditions suited to most community-type tropical fish. Despite a very specific natural diet (see above), blind cave fish remain healthy on almost any commercial fish food – I have successfully used a mix of omnivore flakes and pellets, along with frozen foods. They ravenously devour black worms, brine shrimp and such, and are especially fond of crushed crickets and other insects. Their reaction to insect food brings, at least to my mind, an image of feeding behavior in their native cave. At feeding time, they compete quite well with other fish and rarely require special attention.

Blind cave fish are placed within the order Charachiformes, an extremely diverse group of fishes containing well over 1,500 species, including tetras and the infamous piranha. I will write about piranhas in a future article, and will include photos of some that became “attached” to me while I was seining for knife fish in northern South America. Until then, please forward your comments and questions. Thank you. Until next time, Frank.

A fascinating account of the first expedition to collect blind cave fishes, including original drawings and photos, is given in Zoo Expeditions, by William Bridges (William Morrow & Co., 1945). Long out of print, this book is well worth searching for.

An interesting article on the evolution of eye regression in this fish is posted at:
http://findarticles.com/p/articles/mi_qa3746/is_199809/ai_n8816250

Thanks Frank,

Until Next Time,

Dave

Amazing Coral Story

With this weeks passing of Earth Day 2008, I thought I would write a blog about this great article that I had read recently on www.sciencedaily.com. Some of the darkest days in U.S history involve the nuclear weapons use and testing during and after WWII. Most people learned about the bombs dropped on Japan during WWII in history class, or from family members who lived in that era.

Much less well known nuclear testing was done in the years following WWII as the cold war escalated, and the demand for bigger and bigger bombs grew. From 1946 to 1958 the U.S. Government conducted nuclear bomb tests on the remote Pacific Island Group of Bikini Atoll, which is part of the Marshall Islands. In 1954 the U.S. detonated, what was at the time, the largest hydrogen bomb ever tested. The bomb was code named Castle Bravo, and was 15 megatons (1,000 times more powerful that the bomb dropped on Hiroshima). The blast vaporized 3 islands, raised the water temperature to 55,000 degrees, and left a crater that was over a mile wide and more that 200 feet deep. Needless to say, there was nothing left of what was a thriving tropical island group and surrounding reefs.

Enough of the bad news, this story has a happy ending. Recently a group of international scientists returned to Bikini Atoll to see what was there, almost 50 years later. Plant life on the surface had returned, but is still contaminated with radiation (don’t eat the coconuts). What the group found underwater was truly amazing. As they planned their dive into the Bravo Crater, expectations were running wild. The last time the area was surveyed it looked like part of the moon, and was irradiated.

What they found was a thriving coral reef ecosystem that had completely self seeded itself in the once barren wasteland. Porites corals that reached 25ft in the water, huge formations that looked like trees reaching for the surface. The belief is that water currents from untouched neighboring areas brought larval corals to Bikini, where they settled and matured. The corals had recolonized as much as 80% of the habitat in some of the areas studied.

Compared to studies performed at Bikini prior to the testing, the results show that there has been a serious impact on the diversity of corals to the area. The new study showed that 40 species that were documented to have been there prior to testing, where no longer there, and appear to be locally extinct. I found it amazing that what was there had reclaimed space that had felt the worst of what human kind can offer.

This news shows that, given the chance, reefs can recover from even the most severe destruction. Maybe by looking at the species that are thriving in the Bravo Crater, we can use them to as a guide to recolonizing reefs that have been destroyed by shipping, fishing, and pollution around the world. The main thing that I took from the story is that if we as a society can get our act together as far as protecting our natural resources, that Mother Nature can fight back pretty hard if we let her.

Until Next Blog,

Dave