Few data are available on the thermal tolerance of Nile tilapia fish larvae in relation to their immune status and survival. The aims of this work were to evaluate the immune status of one day old Nile tilapia (Oreochromis niloticus) larval stage collected at the beginning (March), middle (August) and at the end (October) of hatching season through morphometric assessment of the larvae parameters including yolk sac diameter, body length and width as well as the expression of some immune-related genes (rag, sacs and tlr), inflammatory (il1b and il8) and stress related genes (hsp27, hsp70). Also, to compare the effect of three different immunostimulants (β-glucan, Vitamin C, and methionine /lysine amino acids mix) on the expression of the studied genes at two variant temperatures (23±1°C and 30±1°C) in experimental study for 21 days. The immune status of Nile tilapia is affected by thermal fluctuation throughout the hatching season reflected by altered yolk sac size, length, and expression of the immune and stress related genes of the larvae, the best performances was observed at the beginning of the hatching season (March). High temperature (30 oC) suppress immune and stress responses throughout downregulation of all the genes under study, mask any effects for the immunostimulants, increased mortality in fish larvae suggesting narrow thermal tolerance range for the larvae compared with the adult fish.
We recommend the use of amino acid mix as immunostimulant for Nile tilapia larvae, it reduce the mortality percentage and improve cellular response. Also the use of β- glucan should be prohibited during this developmental stage of larvae, it induced the highest mortality percentage.

I Abeer F. El-Nahas is a professor of Genetics and Genetic Engineering at the Faculty of Veterinary Medicine, Alexandria University, Egypt science 2012. I completed my practical work of Ph.D. at Hokkaido University, Japan. My research interests lie in the area of Cytogenetics, Molecular Genetics, Gene manipulation, Gene expression, Genetic Toxicology and immunogenetics. I am the Editor in Chief of Alexandria Journal of Veterinary Medicine and serving as editorial board members and reviewers of many well reputed journals.
Thirty three research students altogether awarded Master and Ph. D degrees under her direct supervision and he has over 30 publications in international peer-reviewed journals with citation over 300 times and her publication H-index is 11.
Abeer F. El-Nahas is the co-author of numerous articles published in prestigious journals, including: Fish & Shellfish Immunology, Environmental Science and Pollution Research, Gene, Basic and Clinical Pharmacology and Toxicology, Pharmaceutical Biology, Ecotoxicology and Environmental Safety, Oxidative Medicine and Cellular Longevity, and others