Piranhas

One species, three ways to buy it: wild red belly piranha (Pygocentrus nattereri), listed non-quarantined, lightly medicated and quarantined. Wild-caught, so expect a fish that is genuinely nervous rather than the film-set monster — a startled shoal will hide behind the filter and refuse food for days.

Check your state law before you check the price. Piranhas are prohibited in a lot of places, and an order confirmation is not a permit — if you are unsure, ask me before you buy. Keep them as a group; a lone nattereri is a jumpy, fin-nipped animal. Feed cut fish and shrimp rather than feeder goldfish, which bring parasites and no nutrition worth the risk.