Estimation of age in tropical fishes with low longivity is difficult. Though we are estimating from scales, otoliths or converting length to age. Is there any recents method(s) published to solve this problem!!
I think it is much simple to try to keep such species with long longevity in aquarium/basin conditions during some months and take samples of scale and otoliths to have real observation on relations between length/age and scales/otoliths. I suppose that these species are not too large fishe and it is not too big problem to hold them in aquarium or basins in tropical conditions.
You can examine your specime'n scale and sectioned otolith under SEM, its a bit expensive. There's no other new method so far aside from the usual ones.