I'm assuming that he's in the 5 gallon...
Protecting him from the other fish is probably a good idea, as long as the breeding net is big enough for him.
Cloudy eye is usually caused by stress, malnutrition, or poor water quality.
Check your water parameters, then do daily small (1 gallon or less on your 5 gallon tank) water changes until levels are optimal. If they were already optimal, still do a few water changes.
If eye doesn't start to clear after this, try adding other foods, and/or vitamins.
Hope this helps...