Short Communication:Effects of the addition of a marigold extract to diets fed to channel catfish (Ictalurus punctatus) on growth parameters

The expansion of aquaculture in the last 10 years has made it an important source of protein worldwide. However, increased production, and the culture intensification it carries, results in higher risk of infectious disease due to poor water quality and high stocking densities. Disease has several negative effects on fish, which include reduced feed efficiency, impaired growth and death, representing a direct loss of investment in feed, labour and other inputs. Disease in fish has been traditionally opposed with chemotherapeutants; however, the number of chemotherapeutants available for use in aquaculture has become more restricted as new drugs become available (Alderman, 2002), due to the antibiotic resistance they may induce when used in fish (Belem-Costa and Cyrino, 2006). This has resulted in the search of nontoxic alternatives to ensure fish health during culture, such as plant extracts to be used as appetite stimulators and growth promoters, antimicrobial, antiparasitic, antioxidant agents, and immunostimulants in fish (Syahidah et al., 2015). Furthermore, animal extracts have also been successfully used as fungicides, like those obtained from the sea cucumber, Holothuria leucospilota (Farjami et al., 2014). Natural carotenoids have traditionally been used as dietary colouring agents; however, carotenoids have been found to carry out essential Short Communication