Maximum fish per gallon?

[hopeful1]

Is there some rule to determine the maximum number of fish per gallon, based on their current size?

[Jungle Fan]

Usually at this point someone will cite the one inch of fish per gallon of water rule, however you need to consider if you're using an air pump, if your tank has plants, and how many, if you have surface movement so the water gets aerated, lots of factors can add, or subtract to the amount of fish you can stock. Some species get along well with others, other species are best kept alone.

[hopeful1]

Is that one inch of fish per gallon?

 

[PineSong]

On 8/7/2021 at 4:05 PM, Jungle Fan said:

Usually at this point someone will cite the one inch of fish per gallon of water rule, however you need to consider if you're using an air pump, if your tank has plants, and how many, if you have surface movement so the water gets aerated, lots of factors can add, or subtract to the amount of fish you can stock. 

Right--one inch of goldfish is a very different bioload than one inch of endlers or ember tetras. I started out with goldfish and kept tanks understocked out of necessity, e.g. 2  six-inch fantails in a 40 or 55. Seeing the dozens of fish in a community tank used to freak me out, but now I have learned to consider that many fish have lighter bioloads and all the plants in planted tanks are helping, too.

[PineSong]

On 8/7/2021 at 4:09 PM, hopeful1 said:

Is that one inch of fish per gallon?

 

Yes, but as Jungle Fan pointed out, depends on the kind/s of fish 🙂

[CT_]

On 8/7/2021 at 1:09 PM, hopeful1 said:

Is that one inch of fish per gallon?

 

Yeah.  But its not a great rule.  Assuming you do enough water changes you can add as many fish as you want IMO.  But I don't recommend adding too many.  water changing can get old pretty fast. 

 

You also have to consider if the fish has enough swimming space, which really is case-by-case.

[Guppysnail]

Just a side note how many you add to start is a way different number than how many you can safely end up with. You biofilter needs time to grow with each added fish. 

[Jungle Fan]

Yes, the old rule as I stated was 1 inch of fish per gallon, however as I and all the others stated, aeration, filtration, water change frequency, amount of live plants, surface water agitation, types of foods the fish are fed, behavior of the different species all play into how densely you can stock your aquarium.

[GameCzar]

If you are new, I would recommend less is more.   Give yourself a little flexibility so you can learn how to deal with parameter changes slowly if they occur. 

If you decide on a tank size, there are many of us here that can help you figure out your best stocking options. 

[Jungle Fan]

@Guppysnailhas some great advice there for you, go easy with the fish load if your tank was just recently cycled, or is just about to finish cycling so you are already thinking about adding fish. Snails and shrimp can be safely introduced at that time because nitrite, which is a blood toxin, will not affect most invertebrates because their blood is not based on hemoglobin.

[Scott P.]

I will just add, don't over feed your fish.

Fish act hungry all the time, they are not. A Hungry fish is a healthy fish.

[Streetwise]

I would not like to work out the math advice, but how about fish-per-plant?

[laritheloud]

On 8/7/2021 at 4:11 PM, PineSong said:

Right--one inch of goldfish is a very different bioload than one inch of endlers or ember tetras. I started out with goldfish and kept tanks understocked out of necessity, e.g. 2  six-inch fantails in a 40 or 55. Seeing the dozens of fish in a community tank used to freak me out, but now I have learned to consider that many fish have lighter bioloads and all the plants in planted tanks are helping, too.

As a newer fishkeeper I've been seriously freaked out about overstocking. My 29 gallon is 'full' IMO, with a school of diamond tetras, 3 honey gouramis, 1 thicklipped gourami, 6 corycats, 6 amano shrimp, 4 nerite snails, and 2 mystery snails. My tetras keep breeding and breeding and breeding and it's grown from a school of 6 to about 11, if I've counted the current surviving fry properly. I've been terrified for months that these guys are going to breed to the point of overwhelming the bioload because more keep making it to juvenile/adulthood -- but so far, even with this stocking level, it's a struggle to get any nitrate readings above 5 or 10 every week, and I'm a bit of a nutcase in watching my water parameters.

Your Mileage May Vary in your tank, and there's so many factors that go into what sort of bioload and stocking level a fishkeeper can manage in in each tank.

[Streetwise]

@laritheloud, you must also love plants, right?

[laritheloud]

On 8/7/2021 at 7:08 PM, Streetwise said:

@laritheloud, you must also love plants, right?

I sure do. It's a jungle in there!

[Streetwise]

@laritheloud, start a journal if you haven’t already. I can help you or anyone with a signature.

[laritheloud]

On 8/7/2021 at 7:19 PM, Streetwise said:

@laritheloud, start a journal if you haven’t already. I can help you or anyone with a signature.

I was going to start a new journal for my 55 gallon! Our stand is being delivered on Friday, and I'll be starting set-up and looking for planting suggestions next weekend. 🙂 

[Streetwise]

Take a photo of the empty space to get started!

[Patrick_G]

I suppose the one inch per gallon rule can get confusing but we don’t really have a better rule for beginners. I do like that fishtubers have put Nano fish in their own category so those of us who started with small tanks have a list of appropriate fish to choose from. 

[anewbie]

There are rules like 1 inch to gallon; but they are worthless. The constraints usually have to do with how much swimming room the fishes need and water quality. Also specific species as some species get quite hostile when crowded and need room to establish a territory. I guess for guppies and swordtail the 1 inch rule sort of work but not really as I usually end up with  20 or so fishes (40 inches) in 25 gallons of water. Plants have benefits but they don't actually help that much with regards to water quality of fishes per gallon 'cept for providing hiding places which is very useful when you have territory seeking fishes.

 

So here is a sample tank of mine which has approx 75-85 inches of fish (it is a 29 gallon so 24 ot 25 gallons of water ); yet the nitrate levels stay pretty decent and since you probably can't find anywhere close to the 40+ fishes in this tank it doesn't look that crowded. Now if i were following the inch per gallon rule....

Edited August 8, 2021 by anewbie

[Streetwise]

I would say that plants have a major effect on water quality!

[Jungle Fan]

The one inch per gallon rule is sort of hokey because sooner or later you'll end up with half fish and it really doesn't address filtration, aeration, and specific fish needs, or allowances for extra fish because you might have a jungle of plants going on. In any case fractions of a fish reminds me of statistics, and ever since my research, and statistics and probability classes for communication, and later for nursing I only believe in statistics I have forged myself.😉

[Scott P.]

Do shrimp go by the one inch rule?

[Jungle Fan]

@Scott P. I never bothered to ask them.

Edited August 8, 2021 by Jungle Fan

[anewbie]

On 8/7/2021 at 7:29 PM, Scott P. said:

Do shrimp go by the one inch rule?

I hope not - i have 12 in my 5 gallon tank; and expect to end up with 20 or 30 or more in the not too distant future.