Malformations represent an economic problem due to a lower market value of the products, an increased expenditure on food, a limited growth, supplementary labor for sorting and general handling as well.
Hence, there is significant interest in addressing the potential causes of these deformities. The main purpose of this study is to understand the effects of incubation into hypoxia (low oxygen concentration), acidic pH and high level of ammonia on various early life stages of Nile tilapia with regards to the occurrence of spinal malformation.
Double staining with alizarin red and alcian blue revealed higher incidence of vertebral deformation with fry incubated in hypoxia within 39-45 hours post fertilization or hpf (Condition III) compared to these of 27-33hpf (Condition I) and 33-39 hpf (Condition II). In similarity with the incubation in acidic condition, abnormalities such as paired neural arch, fused centra or joint haemal arch were commonly observed from the 19th vertebrae onward
These results showed that only a deprivation of oxygen during somitogenesis lead to spinal deformities. However, as the ammonia analysis by spectrophotometer indicated a concentration of 0.03± 0.01 mg NH3-N/L, 0.09 ± 0.02 mg NH3-N/L and 0.17 ± 0.02 mg NH3-N/L within our last experiment, it is suggested to increase the concentration of NH4 Cl in order to witness more relevant data.