Meteorological variations and global warming frequently produce serious losses in fishing stocks and fish production. The rate of fish production depends on climatic variation and demand more prudent management of natural sources, attention to technological action and more specific knowledge of the fish and the emergent pathogens. Temperature affects the development of parasites and pathogenic bacteria and may also have effects on the resistance of fish to disease. Certain environmental conditions are considered door openers to opportunistic pathogens and important initiators of stress. Global warming and worsening of other environmental parameters causes an alteration of the immune-response, with a reduction in the resistance of fish and increases the occurrence of various diseases of fish. Climate change cans increase pathogen development and survival rates, disease transmission, and host susceptibility. Disease in fishes is caused by the infection of various types of bacteria, viruses and fungi. This type of disease has been noticed in many states of India.