Kausik Mondal

Evaluation of fermented fish offal in formulated diet of the Indian major carp, rohu, Labeo rohita [Hamilton]

There has been a considerable research effort towards utilization of less expensive renewable ingredients in fish diet formulations to alleviate problems related to shortage of quality fish meal (Pongmaneerat et al. 1993, El Sayed 1994, Rangacharyulu et al. 2003, Yang et al. 2004, Mukhopadhyay and Mitra 2007). Fish offal, which is generated in large quantities on a daily basis in the urban and sub-urban markets in India, has immense potential to be used as a predominant nutrient source in fish diet formulations. Very few studies have evaluated its efficacy, so far (Giri et al. 2000). In a preliminary investigation we observed the viscera of carps, which are discarded in bulk as offal in the retail fish markets contain a substantial amount of crude protein (31.5%–38.9%) and lipid (40.6%–43.8%) on a dry matter basis (Mondal et al. 2006). Collection of these wastes from the urban and suburban markets, treating them suitably to preserve their nutrients and finally recycling them into fish diet production can have a significant benefit in terms of abatement of pollution of environment as well as reduction in the recurring cost of fish production. Although dried fish, chicken viscera, and related animal by-products have been evaluated previously as protein resource in fish diet formulations (Saha and Ray 1998, Giri et al. 2000), efficacy of fish offal as such has not been ACTA ICHTHYOLOGICA ET PISCATORIA (2007) 37 (2): 99–105 DOI: 10.3750/AIP2007.37.2.06

Partial Replacement of Fishmeal by Fermented Fish-Offal Meal in the Formulation of Diet for Indian Minor Carp Labeo bata

Fermented fish-offal (FO) meal was used as a protein supplement to replace fishmeal (FM) in the formulation of experimental diets for the Indian minor carp Labeo bata. The two supplementary diets, one containing 25% FM plus 25% FO and the other containing 20% FM and 30% FO, showed significantly higher digestibility, growth, and protein deposition than the reference diet containing 40% FM. Partial budgeting of diet formulation and net return revealed that 50% replacement of FM by fermented fish-offal meal rendered a total positive benefit of 134% as compared with the reference diet.