hmm..you may be able to turn their growth rate around by good feeding
sounds like these pacu haven't been fed properly if they are 5 years old.
they should grow at a rate of about 1 inch per month.
i had a pacu in the 90's that I grew to 18" in a year in a half. by that point he was eating two handfulls of floating pellets per day.
try feeding them some good pellets or sticks etc supplementing them with some veggies and see how they do.
nice tank btw. awesome size.
but be warned that if they begin to grow well, you have limited time for them in that tank.[/QUOTE
well i feed them grapes, nuts, corn, limabeans, they eat everything algae wafers. thanks i love the tank, when they outgrow this tank ill give them to the aquarium lol or someone on here. my area isnt into big aquariums it seems