Hi
I'd say-If you can get some, then for sure
"Prazi" is praziquantyal and is the drug. Droncit is a trade name of that product. A intestinal wormer for sheep,cattle, dogs and fish.
If you know a farmer...!
As Ryans has said it won't deal to all worms but your symptons sounded likely as intestinal. 'Still eating but not gaining'.
I go 15ml/100ltrs on my malawi tanks. mix in well, turn off filter but not bubblers for 30 mins.
Vacumn well nxt day.
I do this as a regiular program if tank has new outside inhabitants.