Common Fish Diseases & Caused Reasons

There are literally hundreds of afflictions that can effect the health of farm fish. The most common maladies seen in home aquaculture production are usually either bacterial, parasitic, or viral diseases in origin. Fungal infections are also sometimes seen, and occasionally physical ailments.

Common Fish Diseases & Symptoms in Freshwater Cultured Fish

1. Bacterial Disease

Bacterial diseases are caused by the infection of bacteria in fish body. Bacterial hemorrhagic disease is most likely to harm grass carp. In early stage of illness, fish will show signs of bleeding, which usually occurs in the fin base, gill cover, mouth and lower jaw, if it continues to develop the fish body will have bleeding, the abdomen will be expanding, and red spots will appear at liver and kidney. While Gill rot disease is most likely to harm grass carp and common carp. In early stage of illness, the fish will loss of appetite, the head will go black with increased mucus, if it continues to develop, the gill part will appear the wax yellow and mud gray spot.

2. Parasitic disease

The most common parasitic diseases is Myxospore disease, Dactylogyrusis, Trichodiniasis, Lernaeosis, etc. Common carp were the most susceptible to the Myxospore disease, the carp and Bighead are most susceptible to the Dactylogyrusis, wheel worm is the main invasion of common carp, it is not easy to find in the early stage, and the biggest victims of the Lernaeosis is grass carp, especially the most popular in the summer.

3. Viral diseases

Virus disease is a disease caused by a variety of viruses that invade the body of a fish. Hemorrhage of grass carp is the most serious disease in breeding stage, virus will invade the gills of fish, around the eyes, head, jaw and other parts, and the whole fish is dark black. This disease is more likely to occur in small grass carp, once suffering from the disease, the mortality rate is very high, can reach 80%, and will die in 3 - 2 hours.

1. Natural factors: Temperature of natural fresh water will change with the seasons change, but this change will cause a lot of fish sick and dying in large numbers, because some of the parasites that threaten the health of fish disappear or appear to be affected by temperature change. Dissolved oxygen is the content of oxygen in water, will have a very large impact on the survival of fish. pH in 8.5-7 is the most suitable for the growth of fish, that means neutral and weakly alkaline environment is more suitable for the survival of fish, if pH is less than 5 or higher than 9, it will lead to a large number of fish dead.

2. Water pollution: Now with the rapid development of township enterprises, leading to a lot of sewage into rivers and lakes, and these sewage is the cause of the fish disease, sewage contains a large number of heavy metals and a variety of micro-organisms, will pose a threat to the survival of fish.

3. Feeding fish with fish feed pellets of low nutritions: In different fish growth stages, different formulation should be used to satisfy its nutrition demands! In our previous articles, we have summarized several quality formulations and suitable fish feed extruder, such as Shrimp Feed Formulation and its Manufacturing Process, for your reference only!

Except for the quality of fish feed pellets, Feeding Rate, Frequency, and Timing also influence the growth of farmed fish! All in all, there are certain reasons and conditions, in the general case, the occurrence of fish diseases decided to pathogens, perception of fish body, and the environment.