Effects of different animal baits on the gonad development of YY super-male yellow catfish (Pelteobagrus fulvidruco)

The emergence of novel variety “All-male NO.1” dramatically promoted the development of the Pelteobagrus fulvidraco industry, of which the cultivation of YY super-male was a critical step. Recently, YY super-male P. fulvidraco with intersexual gonad emerged largely, which hindered the development of P. fulvidraco industry. We only found the problem of gonad development in YY super-male breeding with Tubificidae by checking the production and breeding records for nearly 10 years. Therefore, four different baits including Artemia salina, zooplankton, Chironomus plumosus, Tubificidae were used to treat YY super-male for 20 days (11 to 30 days of age post hatching). The survival rate, body length, and body weight of each group were measured at 60 dph (day post-hatching). Tubificidae treatments significantly increased the body length and weight compared with other baits, and the survival rate of fish fed with Artemia salina was significantly lower than fish fed with the other three baits. In addition, we performed histology analysis on gonadal structure at 60 dph and 1 year old and statistics of fertilization rate at 1 year old. As a result, the fish group fed with Tubificidae displayed 75% intersexual gonad and 25% testis without seminiferous lobule, and the fertilization rate was only 36.70%±4.05%, which was significantly lower than that of the other groups. In order to study the reasons for the feminization of YY P. fulvidraco, we measured the estradiol content and found that the estradiol content was low in all four different animal baits. It is speculated that the feminization of YY super-male P. fulvidraco may be caused by the environmental endocrine disruptors (EDCS) enriched by Tubificidae. Therefore, zooplankton or Chironomus plumosus should be fed in the early stage of large-scale breeding of YY-supermale P. fulvidraco, whereas Tubificidae should not be fed.