Old theory challenged. (Tank capacity)

[Jim.Gilbert234]

OK. Next stage ‘challenge the theory’. Last time I was in the hobby (10 yrs) the logic was that tank capacity was based on inch of fish per 5 gallon if memory serves me correctly. Given all the fantastic improvements in the hobby I was wondering if the capacity of the tank had been revisited. I am in the process of putting 1 inch sand in tank and around 25kg of rock in the tank (RSM E260 with sump). Run refugium with cheato. Skimmer rated to twice tank size (it’s what came with it) usual sponge and socks and the obligatory carbon. Thinking of doing Triton method but not committed yet. So what’s the modern take on capacity. Will it still be 16 inch of fish for the 80 gallons I have (sump and tank combined) or something different and up to date.

 

[MnFish1]

OK. Next stage ‘challenge the theory’. Last time I was in the hobby (10 yrs) the logic was that tank capacity was based on inch of fish per 5 gallon if memory serves me correctly. Given all the fantastic improvements in the hobby I was wondering if the capacity of the tank had been revisited. I am in the process of putting 1 inch sand in tank and around 25kg of rock in the tank (RSM E260 with sump). Run refugium with cheato. Skimmer rated to twice tank size (it’s what came with it) usual sponge and socks and the obligatory carbon. Thinking of doing Triton method but not committed yet. So what’s the modern take on capacity. Will it still be 16 inch of fish for the 80 gallons I have (sump and tank combined) or something different and up to date.

No. For example - you would not put a 20 inch fish in a 20 gallon tank. So the inch thing doesn't work out. Another example - a harlequin tusk - which is 4 inches long probably produces much more waste, etc - than a 4 inch pipefish. Its IMHO more based on common sense than a formula. And - yes I agree with you the more 'stuff' you have filtering, etc - the more you can keep in a given tank

 

[blaxsun]

It's whatever gets along without killing each other and doesn't spike your nitrates over 50.

I have 32 fish in my 160-gallon. They're all at least 1" in length (most are probably 1.5"-2"). Some are 4"-6". Using an average of 3" that places me at 3x the 1" per gallon limit. My nitrates are 2-3ppm with phosphates <0.025 and I feed 6 times daily.

 

[polyppal]

I haven't heard the inch per gallon thing since the early 2000s... Definitely not the way you want to choose livestock.

Start with a few smaller fish appropriate to the tank size, and you can gradually increase so long as the tanks maturing bioload and fish territorial aggression can accommodate it.

 

[shakacuz]

i also try to base it off the fish “type” as well. if a very active swimmer i tend to want to lean for a bigger tank even if the tank i look to put it in fits in the “minimum” side of things.. too many “active swimmer” and room becomes and issue, IMHO

 

[Koh23]

That "rule" was probably invented by stores, so that they can sell 20 fish and 20 galon tank, or similar...

I hear often "can i put xy fish in xy size tank, and always respond - sure u can. Put some more, just look a can of sardines..... Ten of them in such small space and you dont hear them complaining

 

[PatW]

It depends on the fish. Some damsels are so insanely aggressive as adults that it would be one fish per tank. A small, relatively sedentary fish with little mass might have little waste impact on a tank. A chunky tang of the same length would have many times the impact.

And another thing is husbandry. The more filtration, aeration, water changes, nutrient export and so on the more fish the tank can support. However, if you have any real chance of a sustained power outage, you will need to take measures to protect your tank from unraveling and undergoing a crash. The lighter the load, the easier it will be.

 

[Driceftw]

I think it's more so a case of using your best judgment nowadays. As long as everything has its place and space, is happy, and your nutrient export handles what is going in the old adage of x inches for x gallons can easily be thrown to the wayside.

 

[Theulli]

OK. Next stage ‘challenge the theory’. Last time I was in the hobby (10 yrs) the logic was that tank capacity was based on inch of fish per 5 gallon if memory serves me correctly. Given all the fantastic improvements in the hobby I was wondering if the capacity of the tank had been revisited. I am in the process of putting 1 inch sand in tank and around 25kg of rock in the tank (RSM E260 with sump). Run refugium with cheato. Skimmer rated to twice tank size (it’s what came with it) usual sponge and socks and the obligatory carbon. Thinking of doing Triton method but not committed yet. So what’s the modern take on capacity. Will it still be 16 inch of fish for the 80 gallons I have (sump and tank combined) or something different and up to date.

I will readily agree that the ability to process fish waste has improved, but fish temperaments have not - to me the primary consideration for fish capacity has nothing to do with filtration and everything to do with overcrowding, aggression and competition for space

 

[WVNed]

It's easy to tell when you have too many. Some will die until you don't.