Numbers/tank size vs fish per gallon

[loopy]

ok, I know the 'rule'...5 inches of fish per gallon.
Ok, people post that they have or are getting this or that, and have ?? pounds of rock, ?? pounds of sand, so....really there is no longer 55 gallons of water. So then how do you figure the 5 inch rule still at the tank size when all of that takes up so much room, therefor, less gallons of water? This seems to be what I read, going by the 'rule' but not taking in account for the lack of water. Just curious about this.:notsure:

 

[knots]

Hi Loopy, I clicked on your thread thinking I was going to get a good story or at least something funny. Oh well maybe next time. I'm sure no expert but I do know you do have the rule backwards. It's 1" in 5 gal. not the other way. I have small fish and I have 12 full grown inches in a 35 gal. which is 1" in 3 gal. and it works great for me. I'm sure you'll get lots of answers. I'll let you slide this time but next time I expect your thread to have some humor.

 

[lefty]

I don't think the actual amount of water you have in a tank is nearly as important as the dimensions of the tank. You want enough space for each fish to establish their own territory. You also don't want so many fish that your bioload can't handle it. If your displaced water is being replaced by something as beneficial as LR and sand, thus allowing you to increase your bioload, then I don't think the displaced water's missed too much.
-lefty

 

[ophiura]

I would agree and disagree to some extent . With LR and such you are taking up space and this cramps the fish....there is no way, IMO, to cram more fish in there simply because there is more biological capacity, in theory. If the tank is packed full of LR to the brim, it has the bioload capacity for many fish, but there is no physical room for them. It is a pretty extreme example, but fish still need space to swim or they'll be stressed and die. So there is a theoretical trade off, IMO.
The footprint is definitely critical though...as I've mentioned a few times, people often use "30g" to describe a 29g tank. This is 1g difference but actually it is a considerable difference in the foot print - a foot difference. Then I think OCeanic's cube tank is also a 30g. Lots to take into account. IMO, you could in theory have very different fish in the 30long versus the 29.
The 1" per 5 g I think is somewhat overused. It depends on many factors, including whether it is a reef or fish only, if fish only if they are predators or messy eaters versus "reef fish," Aggression or lack of, territorial issues, overall adult size, etc.

 

[lefty]

Obviously no one should pack their tank with so much LR that the fish themselves have no room. The way I meant it was that if the said tank had the recommended 1-2lbs. per gallon of LR in it.
-lefty