Aquaponics is a symbiotic relationship among plants, fish and beneficial bacteria that convert ammonia and nitrite, both toxic to fish, into less toxic nitrate that plants can use. The main challenge in such a system is the imbalance of nutrients between the fish and plants grown, as each has different nutritional requirements. The requirements of fish are met through fish feed and those of plants by supplementing nutrients, especially trace elements, through nutrient solutions, which adds extra costs to the production system. The aim of this study was to design a feed that fulfills a dual role: provide optimal nutrition to Clarias gariepinus and optimize lettuce production.
The experiment was conducted for 60 days in triplicate with two treatments: T1 = C. gariepinus commercial feed (control) and T2 = C. gariepinus commercial feed with Moringa oleifera leave powder; in two separate lines of a deep-water recirculating aquaculture system of three (100 L) containers. The stocking density was 25 juveniles (Mean weight = 49.1±.51g) per tank. They were fed at 5% body weight, three times a day. Lettuce seedlings were simultaneously planted in perforated plastic cups with pebbles and placed in holes on the raft floating on each of the fish tanks.
The fresh biomass of lettuce leaves in T2 recorded the highest weight increase (90.62±0.81 g) which differed significantly (P<0.05) from T1 (57.00±1.23 g). Fish weight gain was significantly higher in T2 (300.3±6.55 g) than T1 (231.9±5.24 g). There was no significant difference (P>0.05) in fish length in T1 (24.93±.16 cm) and T2 (24.89±.13 cm).
This study revealed that the inclusion of M. oleifera as feed additives in C. gariepinus feed improved lettuce growth and fish weight gain. It can be concluded that M. oliefera leaves contains enough minerals that can be used to reduce or even eliminate the need to supplement plants with nutrients in an aquaponics system. It could therefore be recommended that M. oleifera leaves be included in C. gariepinus feed in aquaponics production system.