Food and Spice Plants: ‘Good for Humans, Good for Fishes: Revisited’

Food and spice plants as dietary supplements and alternative therapeutics in fish and invertebrate aquaculture have been considered healthy and safe in many studies because plants are ‘natural’ and therefore considered harmless. Aquafeed is often uncritically supplemented with plant material. However, the widespread belief that plant-based products are green and safer alternatives to their chemical counterparts lacks empirical data to support this claim, and ecotoxicity studies are urgently needed. This chapter provides information on a variety of plants used as dietary supplements for fish and aquatic invertebrates that are known from human consumption. Typically, animals respond with improved immunity and accelerated growth performance; however, in many cases, both traits appear to respond independently. The importance of the gut microbiota is beginning to be understood. Gut microbes can provide short-chain fatty acids from fiber and can promote beneficial and suppress harmful microorganisms. Occasionally, however, no beneficial and even toxic effects at all are seen with dietary plant supplements.