Synthetic chemicals Levamisole, FK-565 (Lactoyl tetrapeptide from Streptomyces olvaceogriseus), Quaternary ammonium compounds (QAC).
Biological substances  
1) Bacterial derivatives MDP (Muramyl dipeptide from Mycobacterium species), Lipopolysaccharide (LPS), Freund’s complete adjuvant (FCA), EF203 (fermented egg product), Peptidoglucan (from Brevibacterium lactofermentum and Vibrio sp.), Clostridium butyricum cells, Achromobacter stenohaliscells, Vibrio anguillarum cells (Vibrio vaccine)
2) Yeast derivatives b-1, 3 glucan, b-1, 6 glucan
3) Nutritional factors Vitamin C and E, n-3 fatty acid
4) Hormones Growth hormone, Prolactin, tri-iodothyronine
4) Cytokines Interferon, Interleukin
5) Polysaccharides Chitosan, Chitin, Lentinan, Schizophyllan, Oligosaccharide
6) Animal and plant extracts Ete (tunicate), Hde (Abalone), Glycyrrhizin, Firefly squid, Quillaja, Saponin (Soap tree)
7) Others Lactoferrin, Soyabean protein, Quil A, Spirulina, Achyranthes aspera (Herb), Mucor circinelloides (Fungi)
Table 1: Immunostimulants evaluated in fish and shrimp.