Influence of water aeration levels on the opercular respiratory beats and selected water quality parameters of heteroclarias fingerlings under laboratory conditions in Minna, Nigeria
A twelve (12) week experiment was carried out to determine the influence of water aeration on the Opercular Respiratory Beats (ORB) and selected water quality parameters of 1,800 Heteroclarias fingerlings of average weight of 1.40 g under laboratory conditions. One hundred and fifty fingerlings were allotted in a complete randomized design into water aeration levels: 0.00(control), 6.00, 12.00 and 24.00 hours respectively as treatments and replicated thrice. The ORB and water quality parameters were determined weekly based on standard procedures .Water quality parameters investigated were not influenced by water aeration except the Dissolved Oxygen (DO) concentration in the control that was significantly (p<0.05) reduced. The respiratory beats (ranged from 51.60±5.94 to 53.17±3.77operculum beats per minutes) of fishes aerated within the investigated range of 6.00 – 24.00 hours were not significantly (P>0.05) different at the end of the 12th week. At the 2nd, 8th and 10th weeks, respiratory beats of the Heteroclarias fingerlings were not significantly (P>0.05) different among the treatments. However, in the 1st and 7th weeks respiratory beats were significantly (P<0.05) higher among the fishes not aerated (131.63±8.35operculum beats per minute) and those aerated (76.33±10.75 operculum beats per minute) for 6.00 hours. The ORB decreased with increase in fish size from week 1 to the end of the study. The research also showed that water aeration had no influence on the water quality parameters except DO of the controlled fingerlings. Water aeration had influence on ORB only at the 1st and 7th weeks of the experiment but no significant influence was recorded during the greater period of investigation. As a recommendation, fish farmers are advised to monitor the dissolved oxygen concentration daily in their ponds to ascertain when aeration is necessary. Findings of this research also remove the fears of maintenance cost of using Air pump.
Keywords: water aeration, Heteroclarias, water quality, operculum respiratory beats, fish size