GROWTH AND SURVIVAL OF LARGEMOUTH BASS WHEN FED DIETS CONTAINING BLACK SOLDIER FLY LARVAE

Ashley Tabibian*, Grant Blank and Dennis McIntosh
 
Aquaculture Research and Demonstration Facility
Delaware State University
Dover, DE 19901
Altabibian12@students.desu.edu
 

Largemouth bass (LMB), Micropterus salmoides, are one of the most popular sport fish in the United States and are commonly cultured for use in stocking programs.  Aquaculture production of LMB is on the rise, increasing from 136 farms to 176 farms in 15 years.  Most of this production is done in ponds.  For the last two years, we have been testing the viability of using LMB in small-scale aquaponic systems.  Diets of these fish are particularly relevant due to their high protein demand, and can represent a significant portion of total production costs.  There is significant interest from small-scale aquaculture and aquaponics producers to use black soldier fly (BSF) larvae as a food source for their fish, as BSF larvae are easy to produce on-site using food waste.  However, not much research has been done to quantify the effect of feeding black soldier fly larvae to aquacultured fish.

The intention of this study is to assess growth and survival of juvenile LMB when fed diets containing various levels of BSF larvae meal.  LMB were produced on-site at the DSU Aquaculture Research and Demonstration Facility (ARDF) as part of a larger restoration stocking initiative.  Broodstock were taken from Phillips landing on the Nanticoke River and moved to the ARDF in March 2017 for spawning in ponds.  Fry were transferred from broodstock ponds and allowed to grow until they were 5-10 cm.  180 fingerlings were moved indoors to a recirculating system for feed training.  Once they were feed trained LMB were stocked into a rack system containing 24 18-L tanks connected to a common filtration system at a density of 5 fish/tank.

Individual tanks were randomly assigned to one of six treatments (0, 20, 40, 60, 80, 100), corresponding to inclusion levels of BSF larvae into the diet.  Feed for the study was prepared in-house by combining ground BSF larvae and commercial fish feed (42% protein, 16% fat) to desired inclusion levels.  BFS larvae and the commercial fish feed were ground, and dried to a constant weight before mixing.  Water was added to the dry ingredients to create dough that could be formed into pellets.  Experimental diet pellets were again dried to a constant weight before use.  

Fish in the experimental tanks will be fed twice daily, with rations adjusted based on fish weight every two weeks.  To ensure that the conditions are adequate, temperature, dissolved oxygen and pH will be checked daily while ammonia and nitrite will be tested weekly.  After eight weeks surviving fish will be counted and weighed to ascertain survival, SGR and FCR.