Cloudy Eyes-

Cloudy eyes can be caused by several causes, outlined below.

1. Physical Injury
The fish could have been injured during transportation, causing the eyes to be scratched.
Symptoms: Look for other scratch markings around the body. Inspect the fish's surroundings for presence of dangerous materials. Often, materials which have sharp edges or rough cutting surfaces find their way into the aquarium. These decorations, while nice to look at, are potentially dangerous for fish, especially aggresive species.

Cure:
-Remove harmful deco (if any)
-Provide hiding places (if fish are fighting)
-Water change
-0.3% salt

2. Water Condition
Sometimes, water in aquariums are not monitored well. This can result in extreme levels of ammonia, nitrite, nitrate, or pH unsuitable for the species.

Cure:
-Large water change
-adjust pH gradually

3. Sudden, Wide Fluctuations
This can happen by adding chemicals to the water without regard for dosage. This can also happen when a large proportion of water is changed. This causes several parameters to swing suddenly, giving the fish no chance to adapt. Especially if the water is not aged first, the high chlorine levels can also be very harmful.

Cure:
-Add 0.3% salt
-Add water conditioner/ water ager.

4. Infection
Infection usually follows if the fish is left untreated due to the above three causes, especially if the fish is weakened on the whole. In the worst senario, the affected fish becomes blind and eventually starve to death. However, not all infections inflict permanent damage and/or cause blindness.

Cure:
-Add tetracyclin
-Raise temp gradually to 32C
-Add 0.3% salt

In All cases, one should observe carefully where the remedy action taken is helping the fish. If not, you may be reading the cause wrongly and have applied an uneffective remedy for your specific case.