# of fish per gallon with sump/refugium

[jagermeister]

The common stocking equation for an aquarium is 5 inches of fish per gallon in the aquarium. Now, is this 5 inches per gallon of water in the system or 5 inches per gallon size of the tank itself? For instance let's say I have a 55 gallon tank with a 20 gallon sump and 10 gallon refugium. I have 85 total gallons in the system. So can I safely stock 85/5=17 inches of fish? Let's forget the crowding issue for the time being.

 

[bang guy]

Originally posted by jagermeister
I have 85 total gallons in the system. So can I safely stock 85/5=17 inches of fish? Let's forget the crowding issue for the time being.
I wouldn't suggest it. For the typical mix of active & docile fish 1" (adult size) per 5 gallons in the display tank is proven to work long term.
I have over 1000 gallons in my system but I only have a 155 gallon display. There is nobody here with any experience that would recommend to me that I could keep 200 inches of fish. It just wouldn't work.
I don't believe that Bio-load is ever a problem in a properly set up & maintained system. It's space. Living space. Saltwater fish are mostly territorial and don't like to share. Get too many and they are constantly stressed. Constantly stressed fish have supressed immune systems and they don't live out their full life expectancy.
If you feel the need to push the envelope then you'll need to consider each fish individually. Active fish need more space than Docile fish. Carnivores need less space than herbivores. Aggressive fish need more space.
I can't tell you how many times I hear "I kept blah blah blah for 4 years in a 55 with no problem". Well... keeping a fish for 4 years that normally lives 10-15 years is a problem in my book.

 

[iechy]

I agree with Bang Guy. The extra water volume does give you a little more room due to increased ability to spread the bio-load but think about a mall during christmas time and ask yourself if you'd like to live their all year long. I would say you could keep more docile fish than an inch per five gallons in the display but I wouldn't go filling up with angels and tangs.