Explanation of options:

• (1) Induced breeding

  • Widely used in Indian major carps (Catla, Rohu, Mrigal) to obtain large quantities of quality seed by using hormonal injections or environmental cues to trigger spawning in hatcheries.

  • This is a standard and essential aquaculture technique.

• (2) Selective breeding

  • Farmers and hatcheries select broodstock with desirable traits such as fast growth, disease resistance, and better feed conversion, and breed from these.

  • This improves strain performance over generations and is routinely practiced.

• (3) Inbreeding – NOT used (correct)

  • Inbreeding is mating between close relatives, which reduces genetic variability and often leads to inbreeding depression: poor growth, reduced fertility, higher disease susceptibility.

  • Because aquaculture aims at high vigor and productivity, intentional inbreeding is avoided; instead, breeders try to maintain or increase genetic diversity.

• (4) Composite fish farming

  • Also called polyculture; Indian major carps are stocked together with compatible species at different ecological niches (surface, column, bottom feeders) to maximize pond productivity.

  • This is a common and recommended production practice, not something to avoid.

Therefore, among the listed options, the technique that is NOT used for aquaculture farming of Indian major carps is deliberate inbreeding (option 3).