Something long thin and white is coming out of my gourami fish under his body?

There are a few possible causes for your gourami fish to have something long, thin, and white coming out from under its body. Some of these causes are more serious than others, so it's important to identify the cause and treat it accordingly. Here are a few possibilities:

- Parasites:

Parasites are the most common cause of foreign objects hanging from fish. Common parasites that affect gouramis include anchor worms, fish lice, and tapeworms. These parasites can cause a variety of symptoms, including lethargy, loss of appetite, and flashing (rubbing against objects in the tank).

Look closely at your fish to see if you can identify any parasites. If you see anything suspicious, you can treat your fish with a commercial anti-parasitic medication.

- Bacterial infection:

A bacterial infection can also cause a white stringy substance to come out from under a fish's body. Bacterial infections are often accompanied by other symptoms, such as red, swollen areas on the body, cloudy eyes, and difficulty swimming.

If you suspect that your fish has a bacterial infection, you can treat it with a commercial antibacterial medication.

- Injury:

An injury can also cause a white stringy substance to come out from under a fish's body. This is especially common if the fish has been injured by another fish or by aquarium equipment.

If you think your fish may have been injured, you can treat the injury with a commercial wound treatment medication.

- Tumor:

In rare cases, a long thin white object coming from under a fish's body may be a tumor. Fish tumors can be cancerous or non-cancerous.

If you are concerned that your fish may have a tumor, you should take it to a veterinarian for diagnosis and treatment.

If you are not sure what is causing your gourami fish to have something long, thin, and white coming out from under its body, it is best to consult with a veterinarian or a qualified aquarium specialist for further assistance.