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.
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.