A major constraint limiting the shrimp production is diseases. Shrimp aquaculture is an important industry in many countries especially Southeast Asia and Iran. In cultured pond, the shrimp may be infected with several pathogens such as several viruses. There are at least six lethal viruses affecting penaeid shrimps production in the world especially Southeast Asia and Thailand. However, known viral pathogen in shrimp is about 20. They have been identified from 1970. Incidence of infection in artificial condition is more than nature. The 6 viruses are very important and they cause serious problem for shrimp cultivation and economic losses. They are consisting of HPV, IHHNV, MBV, TSV, WSSV and YHV. Two of them are highly pathogenic and lethal in shrimp such as WSSV and TSV. Shrimp aquaculture is a successful activity. Despite this success, annual production decreased in the latter because of widespread epidemics (epizootics) caused by new viral pathogens. Molecular diagnostic methods such as PCR are tools to detection viral diseases in shrimp in many parts of the world. Pathological methods and electron microscopy are good tools to detection viral disease especially at the first outbreak. Sanitary methods are the best way to control and prevention of viral diseases.

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Vibrio harveyi is a bacteria. It is a pathogen of shrimp which can cause vibriosis. It cause serious disease in the shrimp post larvae and defect in post larvae production. The aim of this study was to determine the concentration of Sanosil-25® which able to inhibit the bacterium growth. Therefore, Minimal Inhibitory Concentration (MIC) and Minimal Bactericidal Concentration (MBC) of sanosil-25 against Vibrio harveyi was determined by tube dilution method which recommended by National Committee for Clinical Laboratory Standards (NCCLS) in the laboratory condition. The results showed that MIC was 15 Part Per Million (ppm) and MBC was 20ppm during 48 hours. It showed that Sanosil-25 is an active antimicrobial agent against vibrio harveyi and can eradicate the bacteria from the water at concentration as well as 20ppm. Therefore, Sanosil-25 may be a useful chemical and for hygienic procedures of water against the bacterium. It didn't determined side effects of 20ppm of Sanosil-25 in shrimp.

Ketamine was evaluated as water-soluble anesthetics drug for a species of fish, rainbow trout (Oncorhynchus mykiss). Fish (size ~20 -~240 gr.) were exposed to a 100-ppm concentration of Ketamine solution (dissolved in water), they were arranged in 4 treatments based on their weight range (Treatment-1= 22.8±3.4 g; Treatment-2= 51.7±4.4 g; Treatment-3= 69.8±5.2 g and Treatment-4= 243.8±20.7 g). Elapsed time for anesthesia duration (stage1 to 3) and recovery duration was recorded. Also, surveillance was evaluated after recovery. Ketamine was effective to cause anesthesia in the fish as 100 ppm concentration. 10 fishes of each treatment (%100) were anesthetized and were induced in stageIII-Plane3 of anesthesia within 2-3 min after exposure to anesthetic solution (Treatment-1= 110.3±3.5 seconds; Treatment-2= 140.0±5.9 sec; Treatment-3= 180.0±5.8 sec and Treatment-4= 190.0±5.8 sec). Anesthesia lasted for 5-6 min while fish were immersed in clean water (water without drug). So, Anesthesia continued for about 5-6 minutes (Treatment-1= 370.3±10 seconds; Treatment-2= 329.6±22 sec; Treatment-3= 300.0±12 sec and Treatment-4= 280.0±5 sec). All fish were alive after recovery. The result shows that Ketamine can produce anesthesia in the fish as a watersoluble drug and it is safe and effective. It may show that Ketamine can be absorbed through gills and can reach the nervous system of fish by blood circulation. The anesthesia duration in every treatment was showed a significant difference compared with other treatments (p<0.05).

From the June to the August 2013, Casualty happened in fish of some ponds of a farm in an area of Kohgiloye-&-BoyerAhmad province. It is a province in southwest of Iran. Three ponds from eight showed more mortality, they have 5 to 20 dead fish every day for 45 days. Afflicted fish have dark body they swimming near surface or at the bottom of the pond and swam unmatched by the flock. Some fish showed hemorrhages around eye and within the oral cavity and exophthalmia occasionally. 45 moribund rainbow trout sampled for dissection and bacteriological examination. Kidney, liver and spleen of moribund fish examined for the detection and identification of bacteria causative agent of disease in rainbow trout. They cultivated aseptically on different media (Blood Agar, Tryptic soy Agar, TCBS Agar and MacConkey Agar).All fish have been infected and suffered septicemia. A type of gram's negative bacterium was responsible of infection and mix infection didn't confirmed. The bacteria were able to growth on MacConkey agar. Detection had done based on clinical finding biochemical tests and staining. Based on it, the bacteria was a bacterium very similar with Yersinia ruckeri which induced infection. Identification continued by PCR method, therefore above result confirmed. Frequency of infectious fish estimated at least 0.375 percent. Application of enrofloxacine for 7 days reduced mortality but could not eradicate the infection so antibiotic therapy repeated 7 days more to eradication.