Lion fish not doing good

[maroun.c]

Hi, a friend of mine has this lion fish since a couple of months when he got 2 of them without any search on waht they eat, they were eating really good the first few days, they ate his shrimps his damsels.... and after that tehy were eating samall fish pieces. 3 days ago one of them is on the substrate and only swims a little with no balance as it swims on it.s back or downwards for a few seconds then restes again on the rocks or sand. no spots of any kind no skin abrasion, normal respiration, clear eyes. it had developped cloudy eyes 2-3 weeks ago but recovered from it. tankmates are:
1 clarcki clown
1 semi circulatus
the toher lion fish
2 damsels that have not been eaten yet.
a couple of hermit crabs, a sand sifting star
also he's got 4 small sand anemones and one small anemone which is whitish with small purple tips don't know if it's bleached or if the white is the natural coloration.
2 stones with anthelia on that is being consumed by his semicirculatus and GSP that got bleached i believe, for now all the polyps are totally white even at the stalks level.
his filtration is with a wet dry filter no skimer and no DSB fluorescent lighting only.
Any ideas about what the lionfish condition and what he should be checking on.