A. Causes: Streptococcus agalactiae, S. iniae,
B. Characteristics of pathogens:
- Gram positive bacteria, small round shape (cocci), joined to resemble chains, non-motile, transparent and smooth colonies.
- Streptococcus iniae bacteria often infect sea water fish farming; whereas S. Agalactiae is more commonly found in fish cultivated in fresh water.
- The attacks of both types of bacteria are generally chronic-acute.
- The type of fish that is often reported as streptococciasis is tilapia.
- Streptococcus spp infection organ. Found in the brain and eyes of fish, it is called "the syndrome of meningoencephalitis and panophthalmitis", and fish infected with this disease often show abnormal behaviors such as swimming spasms and prominent eyes (exopthalmus).
- Bacterial infections occur due to the physical condition of the fish which decreased due to high density, malnutrition, poor handling, organic matter in ponds which are very high dissolved, the dissolved oxygen content in the pond is low, the quality of water in the pond is bad, changes in water temperature that is too extreme.
- Attack of this disease can cause death 30-100% of the total fish population during cultivation; and this disease is a potential obstacle that must be anticipated with regard to the program of intensification and improvement of national tilapia production.
C. Clinical symptoms:
- The level of appetite of the fish decreases, the body is weak, the body is dark, and growth is inhibited.
- Fish becomes dark under the jaw, protruding eyes, bleeding, stomach swelling (dropsy) or wounds that develop into ulcers.
- The movement of the fish becomes nervous and bleeding occurs on the gill cover (operculum).
- Isolation and identification of bacteria through bio-chemical tests.
- Detection of bacterial genes through polymerase chain reaction (PCR) technique.
- Disinfection of cultivation facilities before and during cultivation;
- Prevention of fish seeds through anti-Streptococcusspp vaccination;
- provision of immunostimulant elements by adding vitamin C to fish feed regularly;
- reduce the level of dissolved organic matter and / or increase the frequency of replacing new water in the cultivation medium;
- integrated fish health management techniques (fish, environment and pathogens);
- herbal treatment can be done using Babandotan Leaves (Ageratum conyzoides L.) This treatment is done by distributing the fresh Babandotan leaves to the pond evenly or can be given as fish food with a dose of 30 kg leaves for 100 kg of fish for 5- 7 days.