How big a tank
The tank has to grow with the fish:
- 1,000 gallons A real build for a redtail of two or three feet.
- About 2,600 gallons 12 by 8 by 4 feet, about 10,000 liters. The right size for one fully grown fish.
- 4,500 gallons and up For a group of adults. Even a 13 by 13 foot tank gets small for several four footers.
A four foot female needs to turn around without bending, so footprint matters more than depth.
Setting it up
Bottom. Skip gravel; it can be swallowed or caught in the gills. Bare bottom or large smooth pebbles work best, and sand is fine if you do not mind it moving.
Equipment. A large biological filter, ideally a sump, so heaters and thermometers live outside the tank where a big fish cannot break them.
Decor. Adults need open space more than decoration, and anything in the tank must be too heavy to move. Juveniles like cover: wood, roots, or a length of pipe.