Newbie trying to understand min tank size for various fish

The friendliest place on the web for anyone with an interest in aquariums or fish keeping!
If you have answers, please help by responding to the unanswered posts.


Aquarium Advice Apprentice
Jan 5, 2012
So, while doing research on the hobby and getting familiar with the various common fish people keep you run across a lot of sites with a min. tank size for a fish and I'd like to understand a bit more on how those numbers are arrived at.

After much consideration, it seems like it (should) differs by fish (specie). And there are various considerations for size, like distance for the swimmers, or volume for the poopers (rather less volume for the thin/pencil fish). Are there other considerations? Vertical height, I guess for living space...

I'd just like to get other people's input on this topic, I like knowing why things are the way they are.

Most of them are based on exactly the reasons that you stated. Some other stocking guidelines are based on how big of a territory a fish keeps
Liveaquaria is a good source for stocking info for sure. Sometimes they tend to stray on the large end of tank sizes for some fish though
Thank you Mebbid and Justin for your replies. It really helps get others thoughts when you just don't know.

I was looking at the various Lionfish breeds that are common to this hobby and was wondering why the tank size was on average 75 gallons for the Volitan specie (120 on LiveAquaria) since I'm used to these fish being relatively slow movers, often times just hovering. Then I started looking at the length of the tanks and not until you get to the 125G size do the tanks get any longer, so that led me to wonder if the fish just needed the water system volume, and more generally to my original question, how do you know why.

After posting I also found a video of a Volitan in a 4' tank (probably 55G) and then I realized how big a 15" Lion really is, poor guy. Also, to note the 120G recommendation from Live Aquaria get the fish in to a 6' long tank, which may explain how that site decides its recommended sizes.

Anyway, I'm sort of rambling now so ill stop.
Yeah, the volitan is a surprisingly big fish. But they are also poo machines which may contribute to the suggested tank size.
Top Bottom