(Pantodon buchholzi)
African butterfly fish are not a shoaling fish, so you can have one in your tank and he'll be perfectly happy alone. They get along well with other fish if the others are not top-dwellers. Large floating plants are okay, like plants that aren't duckweed. They get along great with bottom feeders and mid-dwellers. They need to be in at least 20 gallons, with preferably more surface area than depth. They're great jumpers, so you'll need a hood with any holes covered.
Butterfly fish come from west Africa; they're native to Nigeria, Cameroon, and Zaire. The waters are still or slow-moving and with plenty of plant cover.
Sexing butterflies isn't too difficult. The male is slimmer than the female, though that is hard to distinquish unless the female is fat due to carrying eggs. The rear edge of the anal fin of the male is a convex curve and the fin rays form a tube, which is the genital organ. The rear edge of the female anal fin is straight. (The one pictured is a male.)
Butterfly fish are adaptable to many aquarium parameters. They thrive in soft, slightly acidic water with a pH between 6 to 7 and dH between 1 to 10. They can tolerate any pH from 5-8 and dH between 1-19. An ideal temperature for them in the aquarium is around 75-82F (24-28C).
Butterfly fish grow to about 4 inches, sometimes 5. They often accept flakes and pellets made for carnivores, but they love live and frozen foods as well. They will eat small surface fish as well. Mine gets a lot of live crickets and sometimes gets frozen bloodworms and brine shrimp. He also likes freeze-dried bloodworms.
African butterfly fish are not very pretty in color; brown or olive green with unsymmetrical, odd patterns. They have an upturned mouth and big eyes that make them look angry and evil. The pectoral fins are large and wide, making the fish look like a butterfly from above; they help the fish glide above the water to avoid predators and catch flying insects. Butterflies have large fins and a long tail, so they can't be with very nippy fish.
Pros:
-they look awesome
-they're entertaining to watch as they eat live foods
-they have cool color patterns
-they're freaking awesome with their poison-filled tentacles!
Cons:
-they aren't the prettiest colors
-they can't stand other top-dwellers
-they may eat smaller fish
-they need to have a cover for the aquarium
(12/18/2010 EDIT: I always wondered why my tiger barbs didn't nip at Maxwell's fins. A few people at the Aquarium Store today told me that Butterflies were poisonous! The small tentacle things off their ventral fins are venomous like a lionfish. It'll kill other fish, but feels like a bee sting to humans; if you're allergic to it, you can have very bad reactions.)
