Aquaculture’s rapid expansion emphasizes the critical importance of water quality for fish health and productivity. Innovative systems like split-ponds (SP) and pond-side tanks (TK) have been used for cultivating Largemouth Bass (LMB) while addressing challenges such as cannibalism and feed fluctuations. These systems also enhance water treatment through the nitrogen cycle, a fundamental process in aquatic ecosystems. Nitrification plays a vital role in this cycle by converting harmful unionized ammonia (NH₃), which can disrupt fish cell membranes, then into the relatively less toxic nitrite and nitrate. This study investigates the impact of water circulation in enabling the nitrogen cycle, improving nitrification to effectively transform toxic ammonia into nitrate and alleviating ammonia-related toxicity in the water, thereby promoting the health and productivity of fish.
Three ponds were selected for SPs, three ponds for TKs and three ponds for full ponds (FPs). Each pond had an area of 322.5 m2 (25.8m x 12.5m), and an optimal attainable depth of 1.5 m. SPs were horizontally divided into two unequal sections (25% and 75%) by concrete wall with a perpendicular wall in the larger section extending to facilitate U-shape circulation. Water circulation was further governed by paddlewheel, gate, submersible pump, and piping. Tanks were adjacent to fishless full ponds; water was circulated by pumping water from the nearest part of the full pond into a tank, then drained to the farthest part of the full pond. Each system contained 1250 fingerling LMB, with an average size of 58.02 mm (± 2.71). The experiment ran from June to Sept. 2024. Water samples were collected in 18 different locations for weekly measurements of physiochemical variables: low & high range ammonia, nitrite, nitrate, total organic carbon, total nitrogen. Temperature and pH were measured daily.
Data processing is ongoing, but preliminary analysis of unionized ammonia (NH₃) concentrations across the treatment ponds has provided initial insights. Early results suggest that NH₃ levels follow the trend TK < SP < FP (Figure 1), with a statistically significant difference noted between FP and TK (P = 0.0061). Given the equal stocking density of fish, the presence of water circulation in TK and SP may partially explain these observations. Final conclusions will be discussed in the oral presentation.