Freshwater walrus. Also known as the giant bony tongue fish. The largest freshwater fish. Native to the Amazon.

Carnivorous predator.

Smaller fry are not very expensive and quite elegant. Can be fed small fish, shrimp, loach or pieces of meat (poultry, livestock) can also improve the diet by feeding some carnivorous feed (should need to be domesticated by baiting) clams, seafood minced meat puree frozen cubes (need to be homemade) or insects (crickets, centipedes, earthworms) ...... and more... ...

When they grow up they can still be fed all of the above. Insects and fodder can then be ignored. The other food changes would be to feed larger portions.

Attached pictures are from the internet.

P.S. The darker one at the back is the original color Battle Ship (Fortune Fish) 2 of the same are Crown Mimas.