Which fish species work best in biofloc and where do I buy seed?

Hardy, air breathing or tolerant species do best in biofloc because the high stocking density is stressful. Commonly used ones are tilapia (where allowed), pangasius, koi carp, magur and pabda, since they tolerate crowding better than rohu or katla. Buy fingerlings only from a government or reputed registered hatchery so you get the right species and healthy, uniform size seed, and avoid roadside sellers. Your district Fisheries department can give you a list of approved hatcheries and also tell you which species are legally permitted in your state, since some like certain tilapia strains are regulated. Stock at a size and density your aeration can actually support, and never overstock just because a video promised big numbers.