How fast do fish REALLY grow?

[Dekz]

Seems like every time I see a fish that I really like, I do some research and find out that they grow to be 12" or even larger.

Frontosa, Iridescent Sharks, Plecos, etc.

But how long does this take? I know, you are going to say that they are way too many factors, etc, but ballpark it. 1 year, 5 years, 10 years, more?

I mean it would appear that 50% of the fish in any pet store require over 100 gallon tanks in the long run, and I can't imagine that very many people have tanks that size.

 

[SpeedEuphoria]

There are a couple Pleco's that stay smaller, like a Bristle Nose is popular and stays ~4" which would be OK for a 20 long or 29G IMO.

I can tell you that the Common Pleco's get huge, I saw a ~18" one at a LFS.

I'm not sure how long it takes for them to grow, so I didnt answer your question

 

[Jacko]

It depends on the fish, Frontosas are very slow growing, I'd give them 5 years to reach full size. Plecos are fast growing, I have a friend who got a 3 inch common and 6 months later has a 12 inch beast. Iridescent sharks shouldn't even be kept, not matter the eventual plan for them since most home aquaria cannot support a 3 foot fish and taking it back will likely just have it put into another tank too small for it. If you like ID sharks, look into african glass catfish look similar but stay smaller. For plecos, bristlenose stay small, so do rubberlip and a few others. For frontosas, there is a smaller species of tanganikyians that have same color but different stripes like the Neolamprologus tretocephalus, they only get 6 inches.