Nitrogen and phosphorus content in fish tissues of Clarias gariepinus and Lates niloticus harvested from Zaria eutrophic waters

Abstract

The nitrogen and phosphorus level in fish tissues of Clarias gariepenus and Lates niloticus harvested from Zaria eutrophic waters were investigated for a year. Results showed high percentages of moisture and organic contents during the rainy season, while high percentages of dry matter and ash contents were observed during the dry season. The results also showed high mean percentages of water content in flesh (79.81±0.25%) at E2 with highest wet season range as (80.10 – 80.30%), dry matter content in heart (28.04±0.15%) at E2 with highest dry season range as (28.30 – 28.70%), organic content in kidney (94.80±0.12%) at E2 with highest wet season range as (94.80 – 95.50%) and ash content in gills (10.61±0.17%) at E1 with highest dry season range as (9.90 – 10.40%). There were no significant differences in the proximate composition between fish tissues and between species (P>0.05). The result also revealed high mean concentration of nitrogen (2.155±0.259%) and phosphorus (0.083±0.02%) all at E2 in Kidney. Nitrogen is significantly higher in the fish tissues (P<0.05) in all the sites. The results also showed that the levels of nitrogen and phosphorus in the tissues of the species harvested from eutrophic waters is above that of tissues from fresh water, but is within the recommended level for human consumptions.

Keywords: Fish, Clarias gariepinus, Lates niloticus, Nutrients, Eutrophic