Biochar for Sustainable Aquaculture

Due to the intensification of aquaculture in recent years, farmers are using chemicals like fertilizers, pesticides, and antibiotics in the culture system to maximize production within minimum time periods. These chemicals are enhancing production but degrading the environment in the long run. In such a scenario, biochar from agro-waste emerges as a sustainable option to incorporate in aquaculture systems to maximize production without affecting the environment. Biochar is a predominantly stable, recalcitrant organic carbon compound, which can be obtained when biomass is heated to a temperature usually between 300 and 1000°C under low (preferably zero) oxygen concentrations. Biochar has properties like high cation exchange capacity, high surface area, high micro- and macropores, lower bulk density, and so on, so it can be used in aquaculture for various purposes. For instance, when used as a feed additive, biochar improves the feed digestibility, growth, and survival rate in fish and other terrestrial animals. Other uses of biochar in aquaculture include water quality management, pond sediment enhancement, and mineral supplementation in aquaculture systems like inland saline systems, which lack potassium, calcium, and magnesium. Biochar also helps in acid neutralization due to its alkaline nature, thus reducing the need for lime application in aquaculture systems. Furthermore, it has recently been found that biochar can remove antibiotics from the system, which will help mitigate antimicrobial resistance in bacteria. In this context, this chapter will provide an overview of biochar from agricultural waste for application in aquaculture to enhance fish production by maintaining sustainability.