Yes, that should be fine. You might want to blanch it (boil it slightly) to make it less chewy and get rid of any chemicals. Try a small piece and be prepared to hoik it out after 24 hours if it hasn't got eaten. Livebearers do need some veggies in their diet; other good ones are peas, cucumber, spinach, courgette, chard. I find peas are the alltime favourite.