Arapaima in a 480 gallon

one year, maybe more or less. they usually grow around 3-4 inches a month even more sometimes

One year? I had one in a 180 and I bought it when it was a foot long. It grew to 24 inches in 6 months, but stopped growing as quickly. If I had to guess, an arapaima would most likely but not definitely take a a couple of years to grow to that size.

I would assume they are similar to gars, where they grow quickly for a while (gars grow an inch a week if well fed) and then eventually slow down in the rate they grow at, depending on the gar they'll stop at different lengths but in my experience its under 18 inches for tropicals. The only reason I'm not saying this growth will definitely happen is I'm not an expert on arapaima and I don't want somebody to roast me if they do happen to be an expert on arapaima.

Check out my chatuchak thread, plenty of 3 foot arapaimas in 3 foot wide tanks, yeah it sucks for the fish but they can stand it for a little while if you start feeling overwhelmed.

Correction 20 inches not 24, I highly doubt the tank size prohibits growth since there are numerous people with very large fish which outgrow the tank very quickly.

yes i had he grew to 37 inches in 11 months, unfortunately i gave him a way because he was getting too big. But some of them do grow slower

All fish grow at different rates for one reason or another. Friend of mine bought a 12" Pima, he had it for a year or slightly less and it was 17", probably more like 18-19" because a piece of his tail was missing from an injury.

davis101 said:

Holy crap that's awesome. Is that a picture of your pond? How big is that pond?

Click to expand...

yes, it's not quite big 9 x 4 x 3, im not very sure since its a oval shaped pond, never quite measured it correctly.
Arapaima grows at different rates depending on the conditions, feeding, tank size etc... your tank is big and your are a good fish keeper so your arapaima will grow fast.
But it depends some grow much slower than others