A guide to oddballs

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Everybody loves to have a odd or "cool" looking fish in their tank, something that visitors look at and say "what the hell is that?" so more and more shops are starting to stock oddball fish to deal with this demand, unfortunately many pet stores and fish shops have little to no information about the fish they are selling whch can lead to disasterous consequences for you the buyer. This guide while no means complete is intended to help the newly interested oddball enthusiast to make the right choices when choosing their fish and not end up with a 4 foot monster on their hands. Species with a profile in the fish index have a link provided in the name.

Arowana's

There are 6 known species of arowana and all 6 species have one thing in common, they get BIG. These fish should only be bought by those with tanks that have volumes in the multiples of hundreds of gallons.

Osteoglossum bircirrhosum, Silver arowana; The most commonly seen arowana species and unfortunately the largest, silver arowanas are generally peacefull to tankmates that cant be eaten but can grow to nearly 4 feet with 30 inch captive specimins not being uncommon. They will require a tank of at least 300 gallons and should only be kept with fish over 12 inches.

Scleropages jardini, Pearl arowana; As one of the smallest species and in joint place as the second most commonly seen arowana species but at a more affordable price than its cousin the Asian arowana the pearl arowana seems a logical choice for the arowana keeper without a tank the size of a truck, unfortunately despite only usually reaching around 20 inches in captivity S.jardini is by far the most aggressive species and will happily kill any weaker tankmates, keep only with bottom dwelling fish and those that can take a good beating. Minimum tank size 180 gallons

Scleropages formosus, Asian arowana, Usually only seen in truely specialist fish shops Asian arowanas used to comand prices in the thousands making them inaccessable to the average fish keeper, however captive breeding programs have bought the prices of these fish down to levels that while still high are affordable to those who are prepared to care for them properly. With a maximum captive size of around 24 inches and a much more even temper than the jardini the Asian arowana is probably the most suited to aquarium life of all the species. Minimum recomended tank size 180 gallons

Osteoglossom ferreirai, Black arowana; The least seen of the available arowana species the black arowana doesnt grow as big as the other South American arowana O.bircirrhosum but will still attain a captive size of at least 2 feet so still requires a minimum of a 180 gallon tank, this species is very delicate and needs perfect water quality at all times.

The other two arowana's are Scleropages leichardtii (spotted baramundi) and Heterotis niloticus (African arowana) but these are rare and hardly seen in the hobby if at all.


Bichirs

There are 5 species of Polypterus (bichir) commonly seen in the trade with any regularity and a few which are less regularly seen, all bichirs are predators but some are more suitable aquarium inhabitants than others, here is a list with basic details of the 5 most common species.

Polypterus senegalus, Senegal bichir; The most commonly seen and most suited to aquarium life of all the bichirs, with a average full grown captive size of 10" this species can easily be kept in tanks of 30g or larger and is safe to keep with tankmates over 3 inches.

Polypterus ornatipinnis, Ornate bichir; The second most commonly seen and one of the largest bichirs this species is not as suitable for aquarium life as the smaller P.senegalus, ornate bichirs can reach up to 20 inches in length and be as thick as a mans wrist so require large tanks and larger tankmates, minumum recomended tank size is 75 gallons.

Polypterus delhezi, Armoured bichir; One of the medium sized bichirs and quite easily found in good fish stores the armoured bichir is often the third bichir encountered by bichir enthusiasts. They reach up to around 15 inches when full grown and are slightly more predatory than the other commonly seen bichirs, the recomended minimum tank size for this species is 55 gallons and tankmates should be at least 6 inches.

Polypterus palmas, Marbled bichir; Not as common as they once were but making something of a comeback to stores recently the marbled bichir is another small species well suited to aquarium life, they have a maximum size of around 12 inches and can be kept in tanks of 30 gallons upwards, as with the senegal bichir ensure tankmates are over 3 inches to avoid them being eaten.

Polypterus Endlicheri, Saddled bichir; One of the largest bichirs this species is well sought after by bichir enthusiasts and can usually only be found during distinct collecting seasons for high prices. The species can grow to 30 inches and is a active hunter, tanks and tankmates should be as large as possible.
 
Eels

There are 3 main families of eels that fish keepers may come across in fish stores, these are the spiney eels of the Mastacembelus, Macrognathus and Aetiomastacembelus genuses; The moray eels of the Gymnothorax and Echidna genuses and the swamp eels of the Synobranchus, Ophisternon and Monopterus genuses. Of these only a handfull of species are suitable for the average fish keeper and some have specialist needs.

Spiney eels

There are 3 main species of spiney eel commonly sold in fish stores and two that may be found in more specialist stores, these are.

Macrognathus siamensis(aculeatus), Peacock spiney eel; The smallest of the commonly seen spiney eels, this species will only reach a captive size of around 10 inches and is suitable for communities in tanks over 30 gallons with tankmates over 2".

Mastacembelus erythrotaenia, Fire eel; The fire eel is the second largest of the commonly seen spiney eels and can reach lengths of up to 30 inches though 2 feet is more likely in captivity. They are predators and will consume any smaller fish that they can fit into their mouths so tankmates should be over 4 inches. A tank of 180 gallons is needed to house adult fish though the species grows quite slowly.

Mastacembelus armatus, Tyre track eel; Tyre track eels are the largest of the commonly seen spiney eels and can reach lengths of up 40 inches, as with fire eels they are predators and will eat smaller fish. A 180 gallon tank is needed to house adult fish.

Macrognathus zebrinusZebra eel; The smallest of the imported spiney eels but unfortunately the species least often seen, zebra spiney eels rarely reach more than 8 inches in captivity and are the perfect community eel as even small fish such as tetras are ignored.

Aethiomastacembemus ellipsifer; The most commonly imported of the rarely seen African spiney eels. The species is only found in Lake Tanganyika and so needs to be kept in hard alkeline water, a great addition to the tank of the Tanganyikian Cichlid enthusiast.

Other African spiney eels you may be likely to come across are Aethiomastacembelus moorii and Aethiomastacembelus plagiostomus[/i. All African spiney eels are predatory and tankmates should be at least 3 inches.


"freshwater" Moray Eels

Firstly it should be said that there is no such fish as a freshwater moray eel, all members of the Muraenidae family require some salt in the water they are kept in with most species requiring full sea water to survive. There are 4 imported species of so called "freshwater" moray eels which are naturally found brackish waters of which 3 can be found in fish stores with some regularity with the fourth being extreemly rare.

Gymnothorax tile, Snowflake moray; Easily the most commonly seen of the FW morays G.tile can be found in two colour morphs, the common "snowflake" pattern which is black with white spotting and the slightly less common "goldspot" which is black with gold spotting. This eel will require the SG of the water to be atleast 1.005 and this should be raised as the fish grows, in the wild mature fishes are found in full seawater. The fishes appetite is directly linked to the level of the salt in the water and those kept in freshwater may starve to death. G.tile can grow to as much as 2 feet in captivity and as with all moray eels is a voracious predator so tankmates should be large and robust.

Echidna rhodocheilus, White cheeked moray; Not as common as G.tile but sometimes found in more specialist stores E.rhodocheilus can easily be identified from other morays by the two white patches either side of the jaw from which it draws its name. It is the smallest of the FW morays with a adult size of around 18 inches but is quite delicate and can be difficult to keep, the SG of the water should be kept at atleast 1.010 and the use of a protein skimmer is recomended. Eels of the genus Echidna do not prey on fish as much as those of Gymnothorax and are primarily crustacean eaters.

Gymnothorax afer; Sometimes accidently imported with shipments of G.tile but easily told apart by the lack of any spotting on the body. G.afer can grow to 40 inches so needs a fairly large tank but is otherwise identical to Gymnothorax tile

Gymnothorax polyuranodon, Leopard moray; A very rare fish in the trade G.polyuranodon is almost never imported which is a shame as it is the prettiest of the 4 FW species, is reported to reach around 30 inches but almost nothing is known about keeping this fish in captivity.


Swamp Eels

Swamp eels have recently started to become more common in the more specialised shops where they are sold as "tulip eels", small specimins may catch the eye of the oddball enthusiast but these small interesting eels quickly grow into large predatory monsters and only the dedicated fish keeper with a large tank free to use as a species tank is able to house them. There are 3 species imported which are listed below.

Synbranchus marmoratus, Marbled swamp eel; The most commonly imported of the swamp eels this species will quickly grow to around 3 feet in captivity and is a formidable predator, adults should only be kept in a species tank. The jaws are powerful enough to do considerable damage to the unwary owners hands!

Monopterus albus, Asian swamp eel; While not reaching the same size as its American cousin S.mamoratus the Asian swamp eel is still a large and very predatory fish, captive adults top out at around 2 feet and should be kept in a species tank.

Ophisternon infernale, Blind swamp eel; Not as comonly imported and almost identical in appearance and size to M.albus, as with other swamp eels a species tank is recommended.

Other eels

Other eels that may occasionally be seen are the European eel Anguila anguila and other members of the Anguila family and the electric eel Electrophorus electricus which is not an eel at all but a knife fish, these should be avoided due to size and in the case of the electric eel the potential danger of electrocution.
 
Elephant nose fish

Often sold incorrectly as elephant nosed catfish elephant nose's belong to the Mormyrid family of African fishes. Most species in this group have a week electrical organ which is used to find food and defend their territory from other elephant nose fish, this abilty has been utilised by some water companies as a early warning of poor water quality as the fishes electrical activity increases with stress. These fish are usually sold as good community fish which is unfortunately not true, not only are elephant nose fish territorial but they are also very difficult to feed in a community setting as they cannot compete for food due to their tiny mouths, many elephant nose fish die from starvation. Another problem with keeping these fish is that all Mormyrids are highly sensative to copper based medications which makes treating for ICH and other common aquarium diseases almost impossible in tanks containing elephant nose fish.

Gnathonemus petersii, Peters Elephant nose; By far the most commonly seen of the Mormyrids this fish is territorial and may be aggressive to its own kind, either keep them singularly or in a group of at least 5 with 20 gallons of tank per fish. Like all Mormyrids they require small foods such as bloodworms and tubifix worms and a soft sandy substrate to prevent damage to their delicate mouths. Water quallity must be excellent at all times. A tank of 55 gallons or more should be used as the fish can grow to around 9 inches.

Campylomormyrus tamandua, Long nosed Elephant nose; Not as common as Peters Elephant nose the longnosed elephant nose is very aggressiv to others of its own kind and should only be kept alone or with other large but non aggressive slow feeding fishes. They grow to around 15 inches and so need a tank of around 100 gallons to be kept properly, as with other Mormyrids water quality needs to be excellent at all times.

Petocephalus bovei, Baby Whale; This Mormyrid lacks the "elephant nose" and so is not as easily recognised as the last two. They are seldom seen in the trade only being occasionally imported from West African exporters. These will grow to around 4 inches and like other Mormyrids are territorial amoungst their own kind, if kept in a group keep only one fish per 20 gallons of tank volume. Care is the same as other elephant nose fish with small foods, sand substrate and excellent water being required at all times.
 
Flounders (soles)

These small flat fishes which are occasionally seen in fish stores hold a almost instant attraction to the hobbiest looking for something different and are casually sold by most fish stores as freshwater fish, unfortunately all but one or two species are not freshwater and will soon die if not moved into a brackish enviroment with a SG of atleast 1.005. The most commonly imported species are those from the Brachirus genus all of which are brackish dwelling fishes from the coasts around SE Asia and Australia, sometimes you will find species from the Achirus genus which can be identified from Brachirus by their more round shape rather than the elongate shape of the Brachirus species. The Achirus genus has at least one FW representitive in the species Achirus achirus or the Peruvian sole as it is commonly called, this is the ONLY commonly imported FW flounder so all others should be assumed to be brackish unless research proves otherwise.
Other species of flounder that may be found are members of the Trinectes and Rhombosolea Genuses though identification of species is difficult to impossible without internal examinations.

Trinecets maculatus
 
Gars and gar like fishes

American gars, Lepisosteus and Atractosteus species

The American gars are some of the oldest fish on the planet and other than Polypterid species are the only fish known to have ganoid scales which form a hard suit of armour over the entire fish. All species are piscavors and can be difficult to ween off of live feeder fish, a tank with cool water and floating plants is recomended for their care.

Lepisosteus platyrhincus, Florida gar; Florida gars are the most commonly seen of the true garfish species as they are more tolerent of tropical temperatures than other Lepisosteus species and so are easier to breed in captivity in Asian fish farms. Wild adults can reach lengths of up to 5 feet but captive specimins rarely exceed 2 feet, however due to their stiff inflexible bodies a tank of at least 10x3x2 feet is needed for a adult fish to be able to swim and turn. Florida gars can be identified from the similar looking spotted gar by its shorter broader snout and greater ammount of dark markings on the body.

Lepisosteus oculatus , Spotted gar; The second most commonly seen species the spotted gar is probably more suitable for captive life than the Florida gar but with a average captive size of around 20 inches still needs a huge aquarium of at least 8x3x2'. As with all Lepisosteus species other than L.platyrhynchos spotted gars are coldwater fish which should not be kept in tanks with a temperature above 20 centigrade (68f).

Lepisosteus osseus, Longnosed gar; The longnosed gar is instantly recognisable from other gars buy its hugely extended snout. They are not as common as other gars whch is probably for the best due to their large wild adult size of around 5 feet , captive specimins generally remain under 30 inches but due to their long snout need a tank of 10x3x2' or more.

Lepisosteus platostomus, Spotnose gar; The smallest of the Lepisosteus species but unfortunately the least often seen, wild adults only reach a length of up to 24 inches and captive fish are usually smaller, a 8x2.5x2 foot tank could easily house a adult for life. L.platostomus can be identified from L.oculatus by its shorter snout.

Atractosteus spatula, Aligator gar; The aligator gar is truely a fish to keep well clear of, if ever a fish was unsuitable for aquarium life this is it, wild adults have been recorded at over 10 feet in length and captive specimins can grow to 5 feet given space to grow. This fish should be housed in nothing less than a 20x10x5 feet tank which is clearly too large for a home aquarium. Aligator gars can be identified by their olive green colour, short broad snout and double rows of teeth.

Others to watch out for are the Tropical gar Lepisosteus tropicus and Cuban gar Atractosteus tristoechus both of which also get too large for home aquariums. Lastly there is a hybrid of the aligator and Florida gars which goes by the name of "crocodile gar", it is uncertain of how large it will grow but as both parents grow to over 5 feet it can be assumed it will grow at least as large.


Other gar like fishes

Other fish that are often labled as gars by fish stores are pike Characins of the Boulengerella and Ctenolucius species and FW members of the Belonidid family.

Boulngerrella lateristriga Striped gar/pike Characin; A shy nervous scooling predatory Characin from the Brazilian Amazon. The fish need clean highly oxgenated water with a good current and low nitrates. The species grows to around 15 inches and so needs a large tank of at least 6x2x2 with a good cover and tankmates should be over 4 inches to avoid becoming food.

Boungerella maculata, Marbled gar/spotted pike Characin; Similar to B.lateristriga but with a mottled spotted pattern rather than a complete dark stripe along the body. Care is the same as for B.lateristriga.

Ctenolucius hujeta, Rocket gar/Silver gar; Another highly predatory schooling Characin C.hujeta can grow to 2 feet or more in the wild but in captivity a size of 12 inches is more likely. As with Boulengerella species they are shy nervous fish which require clean well oxygenated water and a large well covered tank.

Xenentodon cancila, Needle nosed gar/silver needle fish; Probably the best suited to captivity of all gars and gar like fishes X.cancila only reaches a wild size of around 12 inches and usually remains slightly smaller in captivity. They are shy nervous fish that need a reasonably large tank with a good cover to prevent then from jumping out and harming themselves, they are highly predatory and can eat fish up to nearly half their own size so tankmates should be chosen carefully. The species is very reluctant to feed on anything but live fish so a good supply of healthy feeders is a must.
 
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