First-time goldfish keepers, as well as some experienced ones, are susceptible to goldfish diseases. Experienced keepers can often detect problems early, diagnose the disease correctly, and administer the appropriate treatment.

Greenhands often struggle to identify issues in a timely manner. By the time they notice the disease, the goldfish may already be very sick, making it difficult to bring them back to good health even with the right treatment.

Therefore, it is crucial to learn how to identify early signs of goldfish illnesses.

A healthy goldfish in a tank exhibits the following behaviors: it gracefully swims in the water layer, occasionally going to the surface or the bottom to feed when there is light. In the absence of light, it remains still, suspended at the bottom of the water, resting peacefully.

However, there are instances when goldfish may display abnormal behavior, such as prolonged periods of inactivity or slow responses.

Generally, persistent abnormal behavior in goldfish is often an indication of an underlying disease.

Eight signs that goldfish may exhibit at the onset of diseases:

1. When people approach the fish pond or tank, indifferent goldfish continue to float in the water, appearing lethargic near the walls of the pond or tank. They may lazily swim, startling easily and returning to the water quickly when disturbed.

2. Goldfish in the tank may dart around, swim erratically, spin, float at the surface without sinking, or sink to the bottom without rising. They may even rub their bodies against the tank walls or lie on their sides or upside down in the water.

3. Diseased fish may separate from the group and float in the water. Their dorsal fins may appear bent, pectoral fins weak and less mobile, ventral fins closed, and tail fins weak and drooping. Unlike their usual behavior during feeding, these fish may not approach the owner, or spit out red worms after briefly holding them in their mouths.

4. Diseased fish may exhibit a dull and lackluster body color, become thin, develop shrunken blisters, or display a milky yellow or purple discoloration when swimming. They may only shake their heads without moving their bodies.

Redness, inflammation, bleeding, ulcers, congestion in the fins, erect scales around the abdomen, and rotting of the tail fin may also be observed.

5. Affected fish may excrete long and thin feces with a white mucus-like substance, occasionally accompanied by dark (brown) feces found at the bottom of the pond or tank.

6. The gills may appear congested, pale, or exhibit abnormal colors such as gray-green or gray-white. In some cases, small rice-like particles, gill rot, increased mucus production, or other abnormalities may be present.

7. The fish's body may have an increased amount of mucus, with a white frost-like layer covering its surface or the appearance of small white spots, cotton ball-like clumps, or patches of white fluff.

8. Healthy goldfish will move their eyes horizontally when held in the hand, while sick fish may show weaker or no response at all.

By familiarizing themselves with these early signs of goldfish diseases, keepers can intervene at the right time and seek appropriate treatment, increasing the chances of restoring their fish to good health.