Growth Performance and Haematological Responses of Juvenile Oreochromis niloticus Exposed to Inorganic Fertilizer
Amile Tersoo Jude
Department of Fisheries and Aquaculture, College of Forestry and Fisheries, Joseph Sarwuan Tarka University (Formerly Federal University of Agriculture Makurdi), Makurdi P.M.B. 2373 Makurdi, Nigeria.
Abah Jeremiah Jonah
Department of Fisheries and Aquaculture, College of Forestry and Fisheries, Joseph Sarwuan Tarka University (Formerly Federal University of Agriculture Makurdi), Makurdi P.M.B. 2373 Makurdi, Nigeria.
Athanasius Aondohemen Aende
Department of Fisheries and Aquaculture, College of Forestry and Fisheries, Joseph Sarwuan Tarka University (Formerly Federal University of Agriculture Makurdi), Makurdi P.M.B. 2373 Makurdi, Nigeria.
Oshimagye Michael Ibagye
Department of Fisheries and Aquaculture, Faculty of Agriculture, Federal University Wukari, Nigeria.
Achussah Terwase Solomon
Department of Fisheries and Aquaculture, College of Forestry and Fisheries, Joseph Sarwuan Tarka University (Formerly Federal University of Agriculture Makurdi), Makurdi P.M.B. 2373 Makurdi, Nigeria.
Donald Torsabo *
Department of Fisheries and Aquaculture, College of Forestry and Fisheries, Joseph Sarwuan Tarka University (Formerly Federal University of Agriculture Makurdi), Makurdi P.M.B. 2373 Makurdi, Nigeria.
Annune Paul Amusan
Department of Fisheries and Aquaculture, College of Forestry and Fisheries, Joseph Sarwuan Tarka University (Formerly Federal University of Agriculture Makurdi), Makurdi P.M.B. 2373 Makurdi, Nigeria.
Olufeagba Samuel Olabode
Department of Fisheries and Aquaculture, College of Forestry and Fisheries, Joseph Sarwuan Tarka University (Formerly Federal University of Agriculture Makurdi), Makurdi P.M.B. 2373 Makurdi, Nigeria.
*Author to whom correspondence should be addressed.
Abstract
Agricultural runoff of inorganic fertilisers (NPK 20:10:10) is a growing threat to freshwater aquaculture, yet quantitative data on the sub-lethal effects of the widely used NPK 20:10:10 formulation on Nile tilapia remain scarce. This study determined the 96-h LC₅₀ of NPK 20:10:10 for juvenile Oreochromis niloticus (25.68 mg L⁻¹) and evaluated growth and haematological responses during an 8-week exposure to environmentally relevant sub-lethal concentrations (0.00 (control), 0.43, 0.86, 1.28, 1.71 and 2.14 mg L⁻¹). Increasing NPK 20:10:10 levels significantly elevated pH, total dissolved solids and conductivity while reducing dissolved oxygen. Growth was significantly impaired: mean final weight declined from 3.21 g (control) to 2.38 g at 2.14 mg L⁻¹, and percentage weight gain fell from 39.3 % to 7.2 %. Concurrently, packed cell volume, haemoglobin and erythrocyte count decreased markedly, whereas leucocyte counts rose, indicating progressive anaemia and stress-induced leucocytosis. These concentration-dependent alterations demonstrate that NPK 20:10:10 compromises both somatic growth and haematological integrity of juvenile Nile tilapia at concentrations far below acute lethality. The findings provide critical toxicity thresholds and physiological biomarkers essential for risk assessment and the sustainable management of inorganic fertiliser use near aquaculture systems.
Keywords: Oreochromis niloticus, NPK 20:10:10, haematological changes, sublethal toxicity, LC₅₀, aquaculture