That Fish Blog – Aquarium Advice and Information

Overview
Weatherfishes do not receive nearly the attention they deserve from aquarists, often being purchased as “curiosities” or “scavengers”. This is unfortunate, as they are among the most interesting of all fishes, and are very hardy as well. Their inquisitive dispositions and readiness to feed from the hand can only be described as “charming”. In part 2 of this article we will learn more about how to keep and enjoy them in the aquarium.

Two species are regularly available – the European weatherfish and the Oriental weatherfish (also sold as the dojo loach or Japanese weatherfish). The Oriental weatherfish is more commonly seen in the pet trade in the USA.

Physical Description
Weatherfishes have elongated, eel-like bodies with 5 pairs of fleshy barbels (sensory organs) surrounding the mouth. Their color ranges from metallic and golden tan through various shades of brown. The European species is striped, while the Oriental weatherfish is largely spotted, but both exhibit a mixed pattern of these markings. The Oriental weatherfish is also available in gold and albino color morphs.

Each can reach 12 inches in length, but rarely exceed 8 inches in the aquarium. I at first thought this was be due to a poor diet, i.e. their having to subsist upon “leftovers”. However, a number of individuals of both species that I have kept (including an Oriental weatherfish that reached age 21) also topped out at that length, despite being fed a diet rich in insects, snails and aquatic worms. I did see animals of 12-13 inches in a food market in a Chinese community in NYC. I was told that they had been imported from Hong Kong, but the store owner did not know whether they had been wild-caught or farm-raised. Perhaps, as with other fish species, local populations or races vary greatly in size.

Weatherfishes are classified as loaches, in the family Cobitidae. Many of the 118 species in this family of fresh water fishes, including the coolie loach, clown loach, yo-yo loach and hill stream loach, are popular with aquarists.

Range and Habitat
Both species have a huge range and are equally at home in many types of waterways. The European weatherfish favors rivers, streams and lakes, but is able to tolerate farm ponds and other less-than-ideal habitats as well. The Asian species is found in every type of fresh water environment imaginable. Due to its ability to take oxygen from the air, it is found in stagnant waters and does quite well in swamps, ditches and rice fields.

The Oriental weatherfish occurs from southern Russia south through India and China to Vietnam, Korea and Japan and has been introduced to Australia, Germany, the Philippines, Palau and the USA (Hawaii, California, Idaho, Indiana, Illinois). Much to the horror of loach fanciers, it is used as fish bait in some places, a fact that may in part account for the widespread feral populations. Detailed fieldwork has not been carried out with regard to introduced populations. However, as ravenous predators of invertebrates and fish eggs, it is suspected that they are negatively affecting local species. For this reason, weatherfishes are illegal to possess in Australia and England.

The European species occupies most of Europe except for Great Britain, Ireland, Scandinavia and Greece. Introduced populations have been found in Italy, Spain, Croatia and the USA (Great Lakes region and possibly elsewhere).

Diet
Both species feed largely upon insects, snails, worms and terrestrial invertebrates that fall into the water. They will also feed upon carrion and likely take fish eggs and fry as well.

Reproduction
Rising temperatures and water levels stimulate breeding in both species. Pairs perform “mating dance” of sorts during which the male wraps himself about the female and fertilizes the eggs as they are laid. The eggs are greenish in color and attach to plants and the substrate. No parental care is provided.

Miscellaneous
The weatherfish owes its common name to its unique habit of becoming very active just before a storm. This activity apparently is caused by the effects of barometric pressure (change in air pressure) upon the swim bladder. Weatherfish are among the earliest fish species to have been maintained in captivity – farmers in medieval Europe kept them for their weather predicting abilities, and in Japan they were much valued for their habit of swimming to the water’s surface prior to earthquakes.

Weatherfishes can breathe atmospheric oxygen, a facility that allows them to survive in swamps, rice fields and other habitats unsuitable for many fishes. Interestingly, they have evolved a respiratory system that is quite different than that employed by the “labyrinth breathers” (gouramis), lungfishes and other species that utilize air-borne oxygen. When breathing from the water’s surface, weatherfishes gulp air, absorb its oxygen within the gut and expel the excess via the anus.

During droughts, both species aestivate by burrowing into the mud, where they survive without water for quite long periods. Weatherfishes living in temperate areas spend the cooler seasons below the mud as well.

Please write in with your questions. I am very interested in hearing from you concerning the sizes your weatherfishes have reached, or if you have observed large individuals in food markets. Thanks, Frank.

An interesting article about introduced populations of the Oriental weatherfish (here and abroad) is posted at:http://www.thefreelibrary.com/New+records+for+the+alien+oriental+weatherfish,+Misgurnus…-a0162455040

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

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.  We’d like to take some time to review the most common fish found at your local carnival or fair.

Goldfish

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.

Temperament

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.

Size

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

Feeding

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.

Care

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.

Bettas

The Betta fish, Betta splendens, is another commonly found “prize fish” that you may have the pleasure of become the new owners of. Bettas are one of the most beautiful freshwater fishes that are available in the aquarium hobby; their striking color and ornate finnage are quite remarkable.

History

Bettas are often chosen as prizes because of their ease of care, and ability to do well in very small amounts of water. The Betta is native to areas of Thailand, where they are exposed to times extreme rainfall and drought, which during times of drought can result in little more than a puddle to live in. Unlike most fish, the Betta does not solely rely on oxygen from the water it resides in, it has the ability to breathe air. Bettas are members of a group of fishes called Labyrinth fishes. Labyrinth fishes have a specialized breathing organ, called the labyrinth, which allows them to breathe air at the waters surface, somewhat like a primitive lung. The ability to breathe air allows the Betta to survive in very warm water with little or no dissolved oxygen. This is how Bettas are able to cope with very small fish bowls, and is often how they are displayed and sold.

Habitat

PLEASE do not use this as an excuse to keep a Betta in extremely small environments for extended periods: although they can survive in only a few ounces of water, they will not be happy and comfortable.

Bettas can be kept in unfiltered bowls, provided adequate water changes are maintained (at least 20% per week), and water quality is monitored. Larger aquariums of at least several gallons are preferred, the bigger the better. There are a number of small desktop aquariums that are ideal for Betta keeping.
There is another side of the Betta fishes heritage that there is much controversy surrounding. Another common name for the Betta, is the fighting fish, or Siamese fighting fish. This name comes from the aggressive nature that these fish have towards one another, especially two males. The Thai name for these fish is”pla-kat”, which means biting and tearing fish. When placed in the same tank, two male Betta fish will literally fight to the death. There is a whole world of fighting and gambling involving the Betta in other cultures. Fighting Bettas is not considered an appropriate practice in the hobby.

Feeding & Care

There are many commercially produced Betta foods, in pellet, flake and freeze dried forms. A good varied diet is best. Feed only as much as the fish will eat in a few minutes, take extra care not to overfeed, especially in unfiltered bowls. Bettas prefer warm water, 72-78 degrees, so avoid cool areas like window sills, and hallways when possible. Direct sunlight should also be avoided; this will lead to unwanted algae growth, and temperature fluctuations during the day. While you can not keep bettas together, they can be kept in peaceful community tanks, with other types of fish.

If you have any futher questions about goldfish, bettas or other carnival fish, post them and I’ll be sure to answer. I hope that this has helped all you new fish owners out there, or even peaked the interest of anyone that is considering a fish.

Until next time,

Dave

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

The blind cave fish is found in only one cave, La Cueva Chica (the “Little Cave” – the entrance is only 15 feet wide) near Pujal, in San Lois Potosi, Mexico (related species have since been found in other caves). This fact alone should grant it special status among fish keepers, but there is much more to distinguish it – including a rare glimpse at fish adaptation in progress. Apparently, fish with normally developed eyes live in a nearby river, the Rio Tampaon, and are regularly swept into the cave by the current. There, deprived of light and the need for sight, the eyes degenerate. As time goes on, their descendents are born with gradually more reduced eyes, until the eyeless form emerges. Although I have not read evidence of it, I imagine that inter-breeding with eyeless fish already in the cave may hasten the process.

Fish in pools nearest the cave’s entrance rely upon flies, spiders and other invertebrates for food, while those deep inside subsist upon bat guano, dead bats and, I would venture a guess, fleas and other invertebrates that fall from the bats’ fur.