WWW.WAS.ORG • WORLD AQUACULTURE • MARCH 2025 53 be visually challenging, but males may have larger fins and darker coloration. N. nandus were collected from wetlands of three districts Murshidabad, Bardhaman, and Nadia in West Bengal (Figure 2). The fish were collected by fishermen using various traps and water quality parameters of the habitats were assessed. A total of 50 fish were collected and transported to the hatchery as quickly as possible, packed with oxygen. Experimental tank set up. The aim of this experiment was to explore the benefits of culturing N. nandus in various artificially created habitats, assessing their behavior in simulated natural environments, and examining the impact of planted aquaria in providing a conducive setting. Additionally, the study aimed to evaluate the food acceptance and health of these fish in captivity. Two types of tanks were used: planted or plain glass tanks (91.4 cm x 60.96 cm x 45.72 cm) with hide-outs. The step-wise layering of mud collected from the freshwater zone of Hooghly River, sand and gravel was done to maintain soil aeration. A sponge filter was added to each aquarium to maintain a healthy environment. Because the experiment was conducted in mild winter conditions thermostat-controlled heaters were placed in the aquaria to maintain the optimum temperature (27- 28° C). The aquaria were placed in an area with partial sunlight, allowing better plant growth in the planted tanks. The planted tanks were maintained for one month before stocking fish. During this time the collected fish were kept in a cement tank. The mature planted (A) and plain (B) glass tanks used for captive rearing of N. nandus are shown in Figure 3.Top of Form Results and Discussion Growth. The N. nandus can hide and are somewhat shy in well-lighted aquaria, becoming more active at dusk. They explore their entire tank and prefer areas with less water flow. Growth of fish in each tank type was evaluated after 7 months of culture. Eight N. nandus (7.2-10.3 cm and 7.1-12.3 g) were stocked in a planted glass tank and eight (7.3-10.1 cm and 7.1-12.3 g) were stocked in a plain glass tank with hideouts. After 3 months length and weight of fish in the planted tank were 9.2 ± 0.45 cm and 14.35± 0.86 g, respectively. In the plain glass tank with hideouts fish had grown to 9.4± 0.27 cm and 12.33± 0.95 g. Water quality parameters were similar and acceptable in both environments, including temperature (27° C-30° C), total dissolved solids (252281ppm), conductivity (279396 μs/cm), salinity (179-192 ppt), pH (7.7-8.5), alkalinity (150-158 ppm), dissolved oxygen (7.1ppm) and hardness (176-179 ppm). The growth of N. nandus in a planted tank compared to a clear glass tank offers valuable insights into the potential benefits of enriched environments for fish growth performance. Research indicates that the presence of live plants in aquaria can significantly impact fish growth and overall well-being. Several studies have demonstrated that fish reared in planted tanks exhibit accelerated growth rates compared to those in bare tanks (Hargreaves et al. 2019, Sookhak Lari et al. 2020). The enriched environment provided by live plants offers numerous advantages, including improved water quality, enhanced habitat complexity, and increased availability of natural food sources. Live plants contribute to water quality by absorbing nutrients such as nitrates and phosphates, thereby reducing the risk of water pollution and promoting optimal conditions for fish growth (Bidwell et al. 2018). Additionally, the presence of vegetation provides shelter and hiding places for fish, reducing stress levels and allowing them to allocate more energy towards growth and development (Watanabe et al. 2017). Moreover, the naturalistic environment of planted tanks stimulates natural behaviors in fish, such as foraging and exploration, leading to increased activity levels and improved overall fitness (Steenbergen et al. 2021). Furthermore, live plants in planted tanks can host microorganisms and small invertebrates, serving as supplemental food sources for fish (Pelc et al. 2019). This diversified diet may provide essential nutrients and contribute to improved growth and vitality compared to fish fed solely processed foods in clear glass tanks. Coloration. The N. nandus displayed a striking mottled appearance reminiscent of decaying leaves. Their color ranges from light brown to green with light and dark blotches on the body. These darker patches help them to integrate in artificially created natural surroundings. Interestingly, in a planted tank, the color of the fish remains vibrant and even intensifies over time; however, in a plain FIGURE 3. Two different experimental tanks (A) Planted glass tank, (B) Plain glass tank with hideout. FIGURE 4. Nandus nandus (A) Dull colored with flaccid fins in plain hideout tank, (B) Brightly colored with erect fins in planted tank. (CONTINUED ON PAGE 54)
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