S.o.s.!!

It is possible, but I think that the dimensions offered to the fish is of the utmost concern. Most FHs are reasonably healthy...the fish are causing problems here, too, as pure Trimacs are no longer widely available as some varieties of the Lou Han look exactly like the Trimacs.
 
Good big water changes (~40%) every few days may restore the fishes' appetite, while you work out larger living quarters. You'll probably see a growth spurt when you get these fish into roomier quarters.

I don't think internal parasites is very likely to be the problem, when living quarters are so cramped.
 
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