Fulton’s condition, organ indices and haematological response of catfish hybrid (Heterobranchus longifilis, ♂ x Clarias gariepinus, ♀) to aqueous extracts of leaves of Lepidagathis alopecuroides

Abstract

This study was conducted to assess the Fulton’s condition, organ indices and haematological response of catfish hybrid, Heterobranchus longifilis, ♂ x Clarias gariepinus, ♀ (mean total length, 29.96±2.23cm, SD; mean weight, 207.83±12.63g,SD) exposed to sublethal concentrations of aqueous extracts (0.00, 1.25, 0.50, 0.75, 1.00, and 0.25mg/l) of leaves of Lepidagathis alopecuroides in a daily renewal bioassay for 21days. The Fulton’s condition, organ indices (hepatosomatic index, HIS; cardiosomatic index, CSI; and spleenosomatic, SSI; cardiosomatic index, CSI and renatosomatic index, RSI) and haematological variables (white blood cells, WBC; red blood cell, RBC; packed cell volume, PCV; haemoglobin, Hb; thrombocytes, mean corpuscular haemoglobin, MCH; mean corpuscular volume, MCV; mean corpuscular haemoglobin concentration, MCHC) were assessed at the end of the experimental period. The toxicant caused slight increase only in the HSI (p>0.05), whereas for CSI, SSI and RSI in some of the concentrations the weight were same, lower or higher than the respective control values. Leucocytopaenia and thrombocyotsis, p<0.05 were the most pronounced haematological changes recorded in treated fish compared with the control. Differential counts (neutrophils, lymphocytes and monocytes), blood variables associated with oxygen transport (PCV, Hb and RBC) and red cell indices (MCV, MCH and MCHC) were not negatively impacted by the toxicant. Although the toxicant may not have impaired oxygen transport, it may depress the defence mechanism but enhance clotting of the event of any vascular injury to the fish. In the field where lethal concentrations of the plant material is used to catch fish more severe physiology changes may occur leading the mortality normally recorded during the application of the biocide, Hence the use the plant material for fishing should be checked by appropriate authorities.

Key words: Fulton’s condition, organ indices, haematology, catfish hybrid, Lepidagathis alopecuroides