How many fish can I actually have?

[ChaseB143]

From what I’ve been told, you can’t have very many fish in reef tanks, but then I see people that have tanks loaded with fish.(Way more than what would apply to the rules I have been told) How many fish can be put in 32 gallons?

 

[Oscaror]

From what I’ve been told, you can’t have very many fish in reef tanks, but then I see people that have tanks loaded with fish.(Way more than what would apply to the rules I have been told) How many fish can be put in 32 gallons?

Depends on the fish. I'd say maybe around 4 small-medium fish would be good butt he behavior of the fish matters too

 

[P-Dub]

The number of fish is entirely dependent on what your filtration can handle and not necessarily the volume of water, per se. If you have sufficient live rock and mechanical filtration to handle more than you can likely have more. The limiting factor is the volume of rock you are able to place in the DT and the size skimmer/other mechanical and chemical filtration you have as well as how diligent you are with husbandry. My experience and not a rule by any means. Start with the max amount of recommended fish and then adjust up or down depending on your parameters. If your system is easily handling the bioload, add another fish and then see how/if your parameters change. Be aware that the fish, inverts, and corals will hopefully grow and consequently the load will correspondingly increase over time. While your tank may be able to handle the load of additional fish now, this might not be the case a year or two down the line. Hence the recommendations that are given. It is a lot easier to deal with the growth and consequent bioload by limiting the number of organisms than deal with tank problems and mortality later.

 

[ca1ore]

Those of us long tenured in the hobby routinely break the rules. I have 120 fish in my tank, many of them large. The determinants of fish load are filtration/export capacity and swimming space. Ironically, stuffing a tank full of rock helps with the former but hurts the latter. If you want to ‘overstock’ a tank you need remote filtration.

 

[DeniseAndy]

If you are just starting out, follow the directions from P-Dub. Begin with few and add as the system matures. A lot can depend on what the fish is, final size, temperament, placement in the tank (where it lives), food requirements, so many factors. I hate the "/gallon estimate. Just does not consider all the other factors.

In a 32g, with cover? You could get a smaller wrasse in there, but I would stay away from most fish that are over 4" fully grown. Exception could be a blenny, engineer goby (careful with these guys though- they take a special kind of tank).

 

[ReeferReefer]

Can you give us details on the tank? a 32g AIO will have a much different max load than something with a dedicated sump.

 

[Tamberav]

I have 5 in my 22g AIO and happy with that number. They are all active types so the tank feels pretty busy like a 'reef'. If I were to ever try a 6th it would be a neon goby.

 

[Jesterrace]

From what I’ve been told, you can’t have very many fish in reef tanks, but then I see people that have tanks loaded with fish.(Way more than what would apply to the rules I have been told) How many fish can be put in 32 gallons?

The people who load their tanks with fish generally don't have them like that for prolonged periods of time. You will always find the idiot who puts dwarf angels, tangs, ect. in biocubes and then says "Hey look it works" and then of course conveniently forget to mention that they removed most of the fish within 6 months (which is a terrible practice). Realistically a 32 gallon cube is ideally suited for 4-5 smaller fish (ie 3-4 inches in length max). Things such as Occ or Percula Clownfish, Cardinalfish, Royal Gramma Basslet, Most Gobies and Blennies.

 

[Webslinger]

You can have as many as your filtration system can handle I have 12 - 2- 3" and a 12" eel in my 60. with no aggression. and levels stay stable. If I stopped my reactors it could handle about half that many fish.

 

[CindyKz]

I have 5 in my 32 gal biocube - a Valentini puffer, filefish, yellow headed goby, flame hawk, and a pink streak wrasse. It works because they are all compatible (after some initial hazing from the hawkfish), none of them need a lot of swimming space, and it's a softie tank so I'm not that worried about my nitrates.

 

[saltyhog]

Lot's of good advice above. Please also consider the behavior and adult size of the fish. Sometimes you have to stop adding fish, not because of reaching the limits of your filtration but because of interactions of the fish types/individual idiosyncrasies.

 

[Kimberely]

The number of fish is entirely dependent on what your filtration can handle and not necessarily the volume of water, per se. If you have sufficient live rock and mechanical filtration to handle more than you can likely have more. The limiting factor is the volume of rock you are able to place in the DT and the size skimmer/other mechanical and chemical filtration you have as well as how diligent you are with husbandry. My experience and not a rule by any means. Start with the max amount of recommended fish and then adjust up or down depending on your parameters. If your system is easily handling the bioload, add another fish and then see how/if your parameters change. Be aware that the fish, inverts, and corals will hopefully grow and consequently the load will correspondingly increase over time. While your tank may be able to handle the load of additional fish now, this might not be the case a year or two down the line. Hence the recommendations that are given. It is a lot easier to deal with the growth and consequent bioload by limiting the number of organisms than deal with tank problems and mortality later.

So where can I find this information on max number of fish for my 6 foot, 125 gallon tank? I currently have 14 fish in my tank, but the majority are very small (green chromis, azure damsels, ocellaris clowns, royal gramma, etc) and my tank just looks so empty. The only fish I have that would be considered medium sized are my 4 lyretail anthias and my kole tang.

 

[Rogergolf66]

Ok most of this info is good. But we are missing one major thing..... dont forget about life support what can your tank handle when all is running perfect is one thing. What about during a power outage for example? My tank honestly could probably handle 50-75 fish with my filtration and the size of the system I have 80 gal refugium and a massive 10onch 4ft tall skimmer with multiple pumps, but I have more like 20 fish I would like to add more fish but if you plan to keep your tank for decades you also need to plan for emergencies too. Yes I have automatic batter backups on my power heads. And yes I do have a generator to but I just dont feel safe pushing my bio load so hard. This has alot to do with my comfort level. Tha being said also the amount of fish will also depend on how old the tank is. An established 5 year old system with the same filters as a 3 month old tank the 5 year old tank can handle more bio load then a new tank.

 

[rkpetersen]

Here are some stocking 'rules'/suggestions that have been published by various experts over the years. It's quite a range. It can be educational computing the recommended bioload for your own tank by each measure, to get a rough idea of where you want to be on the bell curve of fishkeepers.

1. 1" of fish (not including tail) per 2.5 gallons of water.
2. 1 medium size fish (2-3" each) per 2 gallons of water.
3. 6-8 medium size fish (3-4" each) per 27 gallons of water.
4. 1 medium size fish per 10 gallons of water.

 

[Kimberely]

Here are some stocking 'rules'/suggestions that have been published by various experts over the years. It's quite a range. It can be educational computing the recommended bioload by each measure, to get a rough idea of where you want to be on the bell curve of fishkeepers.

1. 1" of fish (not including tail) per 2.5 gallons of water.
2. 1 medium size fish (2-3" each) per 2 gallons of water.
3. 6-8 medium size fish (3-4" each) per 27 gallons of water.
4. 1 medium size fish per 10 gallons of water.

Thank you! This helps.

 

[MikeL152123]

I have 10 in my JBJ 45 and am planning on taking 2 if not 4 out. I just think it will make the water quality better even though I have a solid skimmer and do weekly 5 gallon water changes. Personally I would do 5 maybe 6 in a 32 and just spread out the water column. Get 1-2 bottom fish if you have a sandbed, 1-2 that like to hang around the rocks/coral and 1-2 active swimmers

 

[PatW]

Like everything else, it depends.

Aggressiveness. I had a friend who started a freshwater community tank with a jewel chiclid. Of course, the small jewel quickly murdered everything else. So if you deal with aggressive fish, things are problematic.

Size. For awhile, there was a someone catching Goliath grouper fry for the aquarium trade. These guys get to be 1,200 lbs. I don’t think you will get many of these in a 32 gallon.

Husbandry, If you have little filtration, nutrient export, and water movement, the tank just cannot support much.

Niches. Fish demand certain things. In a small tank, it is critical to put in fish that will not compete for the same things.

Hardiness. If you are pushing the limits, it is really easy for your tank to go off a bit from time to time. Getting hardy fish is a good way to give yourself a margin of error. I do not suggest putting difficult fish into any situation that is not optimum for them.

If you want a fair number of fish in a tank, go with peaceful, small, east fish that are selected to not clash in the tank. And bump up the filtration and nutrient export.

Really, a 32 has a 36” long dimension. If you want more fish, the easiest fix is just up the volume. A 120 gallon only has a 48” long dimension. With four times the volume, it gives much more room for error. I am not suggesting a 120 but if you want to go for more fish, you might think of moving up in size in the future.

 

[playapixie]

From what I’ve been told, you can’t have very many fish in reef tanks, but then I see people that have tanks loaded with fish.(Way more than what would apply to the rules I have been told) How many fish can be put in 32 gallons?

The answer is “it depends.” Primarily, it depends on how mature and stable your tank is. If you have a lot of live rock and the tank has had ample time to mature, and your filtration system (mechanical & biological & chemical) are awesome, you can have more fish than if you have a tank that isn’t mature or stable.

It also depends on the fish in question. Are they small? Large? Aggressive, or shy? Crowding aggressive or even semi-aggressive fish in a small tank is asking for trouble. The more live rock with hiking places you have, the better. If you’ve chosen smaller, peaceful fish, you can have more.

I have an almost 8 year old Solana 34 gallon reef. It currently has 12 fish in it (a pair of clowns, Royal Gramma, Midas Blenny, Tail Spot Blenny, High Fin shrimp goby, & 6 Green Chromis.) For my tank that is probably the absolute max and is pushing it. However, I have ample live rock, a very mature system, and I have excellent hygiene routines in the tank. My tank magically keeps nitrate less than 2 even with that heavy load (ok, it’s not magic, it’s a lot of live rock, maturity, and excellent nutrient export via mechanical & chemical filtration, and a fuge.)

If you want a lot of fish, here are my tips:
-live rock & possibly live sand will get your tank stable faster than dry rock.
-your live rock needs lots of holes and hiding spots. Every fish in the tank will need its own safe spot.
-start with only a couple of fish, ideally the least aggressive/territorial of the fishes you want to ultimately add.
-Allow several months to pass before adding more fish, and only add them one-2 at a time. Give your tank time to develop equilibrium before adding more.
-keep an eye on nitrate. It should stabilize. If it’s continually rising, your tank is probably not mature and stable enough to keep adding fish
-feeding amply will (hopefully) help with aggression between fish, but it will cost you in terms of polluting water
-don’t try to follow any “rule” or formula. Your tank and its inhabitants will tell you if they are crowded or can’t handle the ammonia->nitrate load.

 

[P-Dub]

So where can I find this information on max number of fish for my 6 foot, 125 gallon tank? I currently have 14 fish in my tank, but the majority are very small (green chromis, azure damsels, ocellaris clowns, royal gramma, etc) and my tank just looks so empty. The only fish I have that would be considered medium sized are my 4 lyretail anthias and my kole tang.

Google is your friend. Remember to consider your total bioload, filtration, husbandry, etc., and not just fish in a reef system.
https://www.thesprucepets.com/amount-of-fish-and-aquarium-size-1378335

 

[WVNed]

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