| Popis: |
Exponential growth of urbanization increases the unused rooftop space in the city area. The rooftop fish culture is the alternative way to utilized rooftop space and increases the production. In rooftop fish culture foremost challenge is to maintain water quality deteriorated by feces and leftover feed. The study aim was to identify the suitable plants for evaluating the ability of the plants as a part of the biological filter by extracting toxic compound from the fish tank. Research was designed by setup seven treatments (Tws, Tc, Tts, Tcs,Twc, Tip and Tm) with three replicates each by using seven locally accessible plants (water spinach, coriander, taro stem, Ceylon spinach, water cress, Indian pennywort and mint) for biological filtration. Plant beds of the filter system were prepared by using sand, brick, coal and coir. In each fish tank 50 post larvae (PL) of prawn was stocked properly and 35-40 plants in each treatment bed. Water samples were collected to measure pH, DO, temperature, ammonia, phosphate and ammonium. The water temperature (24oC to 26°C), pH (7.78 to 8.8) and dissolve oxygen (DO) were in the optimum range for fish culture. Results showed that the significantly (Pws (0.96 0.89 mg/l) which was followed by Tm (0.57 0.33 mg/l), Tcs (0.54 0.47 mg/l), Tts (0.38 0.35 mg/l), Twc (0.37 0.23 mg/l), Tc (0.26 0.21 mg/l) and Tip (0.18 0.11 mg/l), respectively. In case of ammonia, the significantly highest ammonia was observed in Twc (0.18 0.19) where lowest in Tws (0.04 0.05) mg/l. On the other hand the highest ammonium was observed in Twc where lowest in Tws & Tc. It was also found that the Tws (water spinach) was absorbed high amounts of phosphate, while Twc (water cress) absorbed high amount of ammonia and ammonium. The Tcs showed high yield of plants vegetables (3000 gm/bed), it might be the cause of higher nutrient absorption. The highest yield of the prawn was found in the Twc (321 gm/tank), because this treatment showed highest amount of ammonia and ammonium absorption the most toxic part for fish production. This research demonstrates that using of plants as biological filter provide significant nutrient recycling and increase the prawn and vegetables production. |
