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In Bangladesh, aquaculture is critically important in terms of providing food and nutrition, sustainable livelihoods, income, and export earnings. Nevertheless, aquaculture in Bangladesh has faced recent concerns due to climate change. Aquaculture is vulnerable to a combination of climatic factors, such as global warming, rainfall variation, flood, drought, temperature fluctuation, and salinity change. Considering the vulnerability of fish production to the impacts of climate change, tilapia farming is one of the possible strategies for adaptation to climate change. The positive culture attributes of tilapia are their tolerance to low water levels and poor water quality with rainfall variation, temperature fluctuation, and salinity change. In fact, tilapia farming is possible in a wide range of water environments, including freshwater, brackish water, and saltwater conditions. We suggest that appropriate tilapia culture strategies with institutional support and collaboration with key stakeholders are needed for adaptation to environmental change.

A 105 day investigation was conducted to measure the impacts of stocking densities at different ratios of Nile tilapia (Oreochromis niloticus) and common carp (Cyprinus carpio)on their growth and rice yields in rice-fish farming systems. The experiment was conducted by randomized complete block design with three replications. The plot size was 6×3 m, 50 cm height with ditch (3×1 m) for fish. Mean initial weight of O. niloticus was 12.2±1.92 g using three different fish stocking densities (4, 6 and 8 fish m-2) in five different ratios (1:1, 1:0, 0:1, 1:2, 2:1) of O. niloticus and C. carpio. At the end of the investigation specific growth rate, total length (cm), final weight (g), and survival rate (%) for fish were estimated. Plant height and tiller number were also calculated. The study showed that fish growth performance, fish survival rate, plant height, number of tiller, and abundance of plankton were significantly affected by culture system (p<0.05). The final weight was higher in 4 fish m-2, followed by 6 fish m-2 while the 8 fish m-2 treatment recorded the lowest growth performance. The survival showed the same trend, the highest survival rate was found in C. carpio - O. niloticus ratio of 1:1 (66.67±9.31%) with 6 fish m-2 followed by 4 fish m-2 then by 8 fish m-2 55.36 ±6.11%, and 49.78±4.17% respectively. The highest rice yield, were found in 6 fish m-2 (5.43) that was significantly (p<0.05) higher than in 4 fish m-2 and 8 fish m-2 treatment. The present study revealed that the suitable stocking density was 6 m-2 with 1:1 for C. carpio and O. niloticus for better growth, survival and maximum rice production.

An investigation was accompanied in the rice field plots with developing an infrastructure of 30 m2 to ascertain the felicitous fertilization effects of the Nile tilapia (Oreochromis niloticus) and the common carp (Cyrpinus carpio) cultured along with the rice fish farming system in the plots. There were setting up three systems to assess the effect of fish species on tiller yield, regarding for fish species i.e. no fish stocking with rice (C), O. niloticus with rice (FT) and C. carpio with rice (FC). Each treatment of fish species cultured with different doses of fertilizer such as (T0) control: without any fertilization; (T1) with 100% recommended fertilizer (RF); (T2) with 75% recommended fertilizer (RF); (T3) with 10 ton compost fertilizer; (T4) with 5 ton compost fertilizer+75% RF, and rice culture with 5 ton compost fertilizer+50% RF. The maximum number of plant in the tiller were found in C. carpio (FC) species (7.02 no/tiller and 82.95 cm/tiller) whereas lowest in FT (6.40 no/tiller and 81.65 cm/tiller) during 75 DAT. In regards of fertilizer application, the highest values were observed in FC with an average of 31.71, 53.28 and 73.06 cm/tiller during 30, 40 and 60 DAT respectively, followed by F0 (31.92, 52.43 and 72.31 cm/tiller at 30, 45 and 60 DAT) and FT (30.28, 49.76 and 67.25 cm/tiller at 30, 45 and 60 DAT) respectively, in which there was found negative significant differences (P>0.05) among different treatments. The rice production in C. carpio fertilizer treatment T4 (7.30±1.86 kg/m2) was significantly higher than those of other treatments (7.16±2.78, 6.83±2.88, 6.67±1.44, 6.17±1.84 and 4.06±1.76 kg/m2 in treatments T5, T3, T2, T1, and T0 respectively). The yields of fish were significantly higher (P<0.05) in treatments T4, (11.70±3.86 kg/m2) than other fertilizer treatments T5 (11.25±3.56 kg/m2), T3 (10.85±5.76 kg/m2), T2 (10.80±5.55 kg/m2), T1 (9.90±4.66 kg/m2), T0 (4.78±3.48 kg/m2) and in FC and also compared to all other fertilizer treatments i