Tank of the Month - # of fish

[OneReef]

I was curious about the 31 fish in the 80g TOTM on ReefKeeping this month. I have 9 or 10 in my 75g and was wondering if I was pushing the limit on my stock. Apparently not, if this reefer has 31 in a 80g. I just wanted to start a civil discussion on what people think a 75g or 80g could accommodate without overdoing it. Maybe I can get some more fish..... :D

[username in use]

There are so many variables, it is hard to just say that you can have x number of fish in x gallons. You need to factor in not only the size of the mature fish, but also what its habits are in terms of swimming, eating, aggressiveness, territory requirements, rockwork, filtration etc etc. I think that some people push the limits of the number of fish that you can keep in a given system, like the current TOTM, but he is obviously very good about maintaining his water quality, or he wouldnt have that kind of sps growth. It also seems like he shose all small to medium sized fish, possibly planning it out before hand, but maybe not. I would say that you could keep a higher number of fish in a tank, if they are mostly small fish that require smaller territories and are of species that will coexist peacefully, and you are meticulous about your maintanence. However if in your 75, you have 2 tangs, a puffer, a lionfish and an eel (5 fish), than I would think it would be difficult for you to add more to that tank without running into water quality issues. However if in that same tank you had 5 neon gobies, than of course you can add a number of more fish. Im sure others will chime in, and Im interested to hear what people think, but it is a very simple question that requires a very complicated answer, as everything in this hobby does. I hope this wasnt too long winded.

Good topic of discussion.

[Seventy]

Well the manufacturer's rating for both of his skimmers combined on a "normally stocked" reef tank is 310 gallons. For an 80 gallon tank that's some serious over-filtration, plus they're mostly smaller fish, Anthias and Chromis.

[Shane Hoffman]

There is alot more to how many fish you can keep than tank size. 30 small fish may not produce as much bioload as 10 larger carnivores. Also his tank may have more equipment/effort put into nutrient export. In the end every tank is unique when it comes to max amount of fish allowed. I monitor my parameters closely and use those readings to determine alot of things.....one of which is...do I have a system that can support more fish?? Am I overfeeding??? etc.......

Then you also have to monitor your fishes behavior to determine if they are over crowded. Do they have enough swimming room. Are they showing signs of overcrowding etc.

You can have alot more fish if you are into small fish that tend to stake out a small section of the tank and stay there. If you want larger fish that need lts of swimming room you wont be able to keep as many.

If I went by number of fish I am sure many would say I am overstocked. But if they paid attention they would realize that almost half of my fish are small, low waste producing, inactive fish.

I guess in the end do some research on your fish choice and the impact they will have on the habitat they are going into. If its a positive impact, get it. If its negative, dont.

[OneReef]

Any more thoughts?

[romanr]

I think that with today's available filtration, bio-load can be managed quite easily. An 80 gallon tank with a large sump, a "super" skimmer, GAC, GFO, refugium and plenty of bio filtration (DSB, live rock) can accommodate the bio-load of more fish than you can realistically fit in a tank. The limitation is going to be the behavior/compatibility of the various fish. I have 8 moderately sized fish in my 65 and there is no problems dealing with the bioload. I could probably get a few more without worrying about the bioload but any more would probably cause chaos because of behavior incompatibilities and territorial overcrowding.

[luther1200]

I don't think anybody should try to add that many fish until they have some experience. The general rules are for people starting out or that never really get into it. But if you spend a lot of time with your tank and are familiar enough with it water chemistry you can know what kind of bio-load it can handle, plus keep the fish happy and stress free.

[Nanook]

I have 35 fish in my 375g and 35 fish in my 470g tanks. Many of them are smaller, but the tangs look cramped to my eyes because of the liverock, corals and other fish.

I think the issue with that many fish in such a small tank is that territory will become an issue. Systems will always strive to achieve homeostasis and that will most likely mean fish die or jump eventually.

[LobsterOfJustice]

I had 21 fish in my 90. Sounds like a lot, but the largest fish was only 4". The rest was anthias, chromis, gobies, etc.