Nitrite implications and its management strategies in aquaculture: a review

Abstract

High nitrite levels are often encountered in intensive and recirculatory aquaculture systems but can also be found in natural waters under certain circumstances. Significant research advancement on nitrite and its implications in aquaculture sector has been made for last few decades, but emphasis on its management aspects has been given due consideration since recent past. Therefore, this review article not only aims to summarize the voluminous published reports on nitrite implications in fish but also recapitulates the research progress made on mitigation/ management strategies. Nitrite exposure has been shown to adversely affect fish and shellfish growth, moulting, blood oxygen carrying capacity, water balance, osmoregulation, ionic homoeostasis and cause endocrine disruption. The nitric oxide produced from nitrite can inhibit several components of steroidogenic pathway leading to reduced reproductive performance. Different approaches and management strategies that have been evolved so far to address the nitrite-associated stress have varying degrees of success. Adopting better nutritional approach like feeding antioxidant or nutraceutical fortified feeds along with effectively functioning biological filters is found to be helpful in reducing the deleterious effects of nitrite in cultured animals. This review paper, containing the plethora of information on nitrite and its management in one place, will definitely act as a ready reference for different stakeholders such as farmers, researchers and policymakers for sustainable development of aquaculture.