Two of my goldfish - Miko and Clide have red spots but a sucker fish named Neko is fine. the matter with them?

1. Epistylis: Epistylis is a protozoan parasite that can affect the gills, fins, and body of goldfish. It appears as small, white or red dots on the fish's body. Epistylis can be treated with medications containing copper or formalin, but it is important to follow the directions on the medication carefully as copper can be toxic to fish.

2. Columnaris: Columnaris, also known as cotton mouth disease, is a bacterial infection that can affect the gills, mouth, and fins of goldfish. The infection can cause white or red patches on the fish's body, as well as excessive mucus production. Columnaris can be treated with medications containing antibiotics, such as erythromycin or tetracycline.

3. Fin Rot: Fin rot is a bacterial infection that affects the fins of goldfish. The infection can cause the fins to become tattered and appear red or white. Fin rot can be treated with medications containing antibiotics, such as erythromycin or tetracycline.

4. Water Quality: Poor water quality can also cause goldfish to develop red spots. This can be caused by high levels of ammonia, nitrite, or nitrate in the water. It is important to test the water quality in the aquarium and make sure it is within the safe range for goldfish.

If you are not sure what is causing your goldfish to have red spots, it is best to consult with a veterinarian or a qualified aquarium specialist.