Stocking Rule - Surface Area calculation

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Aquarium Advice Freak
Mar 24, 2004
Lakeland, FL
Hello all! I have a 60 gallon cube tank and was wondering what everyoen thought about the maximum number of fish for my tank. I currently have Blue Tang, Percula Clown, Rose BTA, and various snails, hermits, and shrimp. I also have a Auriga Butterfly and Black and Yellow Blenny in the QT. Do you think that would be my maximum? Because I was really hoping to get a Flame Angel for my last fish.

I know a basic general rule is one inch of fish per gallon, but my tank is not a normal shape. So, I thought the surface area of the water should be taken into account. Doing this calculation, I come up with 4 fish... but the blenny and clown are both small fish. What do you guys think?

IMO, and this topic gets debated regularly, it's not only tank dimensions that limit your stocking. many factors need to be looked at.

First off, how wide is your tank? my guess is it's not long enough to house a blue tang, but that's a separate issue.

As far as your stocking limit, I believe it also is a matter of your husbandry practices, filtration equipment, LR volume, aquscape and the overall nature of the fish you currently have.

It's good to have lots of LR for its effectiveness as a bio filter as well as it gives you options for aquascaping which helps you create "zones" within your tank. If you can aquascape it to minimize direct lines of sight from other areas within the tank, then you will most likely reduce aggressiveness from territorial issues amongst all fish.

Increasing your stock also means the water gets dirtier faster, so husbandry practices need to be evaluated. Having a GOOD skimmer will also help stretch the rule of thumb slightly too.

Include your dimensions of the cube on the next post and I'm sure many will give you their opinions on your limit.
well, aside from the fact that this is not the issue at hand - she is small... about 2.5 inches. she was my first fish and has been the happiest camper for 3 years now.

anyway, does anyone have any ideas on the stocking number?
Honestly, I also question a BHT in a 2ft. tank. It is a bit cramped for that fish. I am not really a fan of "stocking rules" or any hard and fast rules for SW in general. If you are concerned with overstocking all you need to do is turn to your water parameters. If you have consistantly good levels with no NH3, NO2 and very low NO3 then you are not overstocked. It all depends on type and amount of filtration, feeding schedule and type of fish. Please do not confuse overstocking with pairing the approprate fish to the appropraite sized tank.
... well, i am very concerned with getting the appropriate fish for my tank - ones that are compatible, etc... that is the reason i only have two fish in the aquarium after three years. so, that being said, i think i have my answer now. thanks for the input.
I can tell you that 1" per gallon is no where near correct. As lando said no one knows your tank like you. Water parameter should give you the best idea. Type of fish also has a great deal to do with it. I also agree that a BHT is a bad choice for that tank. Generally speaking, and I mean generally 1" every 5 gal or so is a rough guide.
zuzecawi said:
A tang that stays 2.5 inches for three years? Do you have pictures you could post?
I was wondering the same. Even purchased at 1” (which I have never seen, usually at least 2”) to only grow 1.5” in 3 years is unheard of. They usually grow about 1”-2” per year and most 3 year old tangs I’ve seen are 6”+. The smaller tank size doesn’t really restrict growth that much either.
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