Performance of a Constructed Homestead Aquaponics System Used For Fish Culture and Lettuce Production

Abstract

Two identical Aquaponics systems were constructed to evaluate the growth of Catfish (Clarias gariepinus) and Lettuce (Lactuca sativa) and also to evaluate water quality and nutrient dynamics. A repeated measure design (RMD) was used in all the experiments. Lettuce was grown in three grow beds (GB) containing substrates of gravel and biochar. GB A contained only gravel, GB B contained gravel and biochar in a ratio of 1:1 and GB C only biochar. The fish of 50 grams average weight were reared in two tanks A and B. Fish from tank B had the highest biomass of 5,880 grams as against those from tank A with a biomass of 5,400 grams, tank A had a survival rate of 90% while tank B had 93.33% survival. The biomass and height of lettuce was also compared, GB C had the highest biomass and weight of 16.34 grams and 20.96 cm as compared to GB B 13.3 grams and 12.08 cm and GB A 12.19 grams and 8.87 cm respectively. The physic-chemical parameters of water which include temperature, pH, dissolved oxygen electrical conductivity ammonia nitrite, nitrate hardness alkalinity and biological oxygen demand were measure. It was observed that there was no significant difference (P>0.05) between all the water quality parameters. GB C had the highest 5.8mg/l followed by GB B 5.0mg/l and GB A with the least 4.63mg/l. The nutrient dynamics studied in the experiment are Fe2+, NO3-N, PO4-P, K+, Mg2+, Na+ and Ca2+ in the three grow beds did not differ significantly (P>0.05). In conclusion, biochar can be used as an effective substrate in Aquaponics system for the culturing of plants.