What does it mean if one fish spends and keeps spending all its time hidden in an ornament like never coming out but the other are healthy normal?

Potential Causes:

- Fish Species: Some fish are naturally shy or timid, and they may spend more time hiding than other fish.

- Stress: Fish can become stressed due to various factors, including changes in water quality, temperature, or the introduction of new fish. Stress can cause fish to hide as a way to feel safe.

- Illness or Injury: A sick or injured fish may hide to avoid being preyed upon or to seek shelter.

- Aggression from Other Fish: If a fish is being bullied or harassed by other fish, it may hide to avoid conflict.

Steps to take:

- Determine Fish Species: Research the natural behavior of the fish in question. Some fish are naturally more solitary or secretive than others.

- Check Water Quality: Ensure that the water parameters, including temperature, pH, and ammonia levels, are within the optimal range for your fish.

- Quarantine New Fish: Before introducing new fish to an existing tank, quarantine them for a period of time to ensure that they are healthy and do not introduce any diseases.

- Manage Aggression: If you notice any aggression among your fish, take steps to separate or re-arrange the tank to reduce the likelihood of conflict.