“Tankbusters” are fish that get so large that virtually no hobbyist can provide them with the aquarium they need when they reach adult size. Tankbusters, when they reach adult size, require a 300-gallon aquarium or larger.
The “Big Three” of tankbusters are the pacu piranha, the red tailed catfish and the iridescent shark. Every public aquarium and local fish store already has as many of these bruisers as they want. The problems that come from local fish stores selling these three fish to unknowing hobbyists who need to get rid of the fish shortly after purchasing it, greatly outweigh any inconvenience that might be caused by someone who really wants a pacu, red tailed cat or iridescent shark and is prepared to devote a 300-gallon aquarium to this fish. These three fish should not be sold in hobby, for the following reasons.
1. Pacu Piranhas – get to be 3 feet long and hefty enough that they are a primary food fish in the Amazon where they come from. They are vegetarians, although I am sure that part of the reason some folks buy them is the bloodthirsty appeal of the name.
2. Red Tailed Catfish – get even bigger than pacus. The cute little 4 inch long babies soon get bigger and bigger and bigger.
3. Iridescent sharks – these fish, depending on the species, can grow to 4 feet long and a hundred pounds – a primary food fish in the Mekong Delta in Asia. The real problem is that they are fast swimmers, and they scare very easily. When they are scared they bolt around the aquarium bumping into everything, especially the sides of the aquariums. Some iridescent shark over 8 inches that have been returned to LFS, have badly bruised noses and the eyes are cloudy.
These three fish should not be sold by any local fish store. I strongly encourage you to question any LFS you go into that has these for sale in their aquariums. You can also join the Responsible Fishkeeping Initiative to help keep these fish out of most aquarist’s aquariums.