COMPARISON OF THE PRODUCTION OF BIBB LETTUCE Lactuca sativa REARED IN INDOOR AQUAPONIC SYSTEMS USING LARGE MOUTH BASS Micropterus salmoides VS. NILE TILAPIA Oreochromis niloticus

Aquaponics is a sustainable food production system that combines hydroponic plant growth with fish rearing in a recirculating aquaculture system. Nile tilapia (Oreochromis niloticus) have been are primarily raised in these systems due to their fast growth rates and ability to tolerate poor water conditions. As aquaponics becomes more popular in temperate climates, farmers are looking for alternative fish species more compatible with cool temperature culture and have a higher market value.. However, fish feed is species specific and the major contributor of available nutrients for cultured plants; indicating a need to look at differences in nutrient availability and plant production between cultured species. The largemouth bass (Micropterus salmoides) is a high-value fish that is amenable to culture in more temperate conditions. This study evaluated largemouth bass as an alternative species for the production of Bibb lettuce (Lactuca sativa) and Red Russian kale (Brassica napus) in aquaponic systems.

Researchers evaluated plant growth factors stocked with Nile tilapia and largemouth bass (LMB) in aquaponics. Fish were stocked at approximately 1,400 g per system and fed five percent body weight per day. Tilapia and LMB were fed a floating feed containing 32% and 45% protein, respectively. Bibb lettuce and Red Russian kale were evaluated in successive planting cycles. At harvest total plant biomass in each system was recorded. Sixteen representative samples from each system were collected and analyzed for plant and root weight, number of leaves, leaf surface area, root/shoot ratio, and chlorophyll content. Plant and water samples were collected and further analyzed for micro and macro nutrient content.  

Results indicated that growth of Bibb lettuce in aquaponics with LMB was similar to growth of lettuce grown in systems with tilapia. However, Red Russian kale had significantly greater growth in systems stocked with tilapia than LMB. More data will have to be analyzed to determine differences in the outcome between the two plant crops. Due to results from Bibb lettuce, there may be potential for LMB to be used as an alternative to tilapia in aquaponic systems.