1 inch per gallon rule

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ClearVision94

Aquarium Advice Freak
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Sep 15, 2013
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I want anyone's and everyone's "opinion" on this. It's one inch of fish per gallon right? Live plants help remove the nitrates from the water and you can do less water changes. With a heavily planted tank, could you add a few more fish ignoring the rule but continuing to do weekly/regular water changes?

In my point of view a heavily planted tank with a few more fish and ignoring the rule would be (lack of a better word) equal to a tank with fake plants and accepting the rule...
 
I want anyone's and everyone's "opinion" on this. It's one inch of fish per gallon right? Live plants help remove the nitrates from the water and you can do less water changes. With a heavily planted tank, could you add a few more fish ignoring the rule but continuing to do weekly/regular water changes?

In my point of view a heavily planted tank with a few more fish and ignoring the rule would be (lack of a better word) equal to a tank with fake plants and accepting the rule...

That "rule" is a horrendous guideline for stocking. It actually will not work for almost any fish (even a 1 inch neon tetra shouldnt be in a 1 gallon bowl)
This is not to mention the fact that it doesnt take into effect the differing bioloads of different fish. For example a 3 inch molly is equivelant to like 10 neon tetras. It also doesnt take things like plants into consideration like you said.
 
It's a good beginner's guide but shouldn't be a hard and fast rule. Similarly, aqadvisor.com is another good starting tool to figure out how to stock smartly...but again, is not the word of god.

My personal views on stocking are a little more lax than most people. I think that as long as you can control your nitrates without doing more than one water change a week, don't have territory issues, and have enough room for the fish to swim and be healthy, it's fine. I know that last one is opinion based, but use your judgement. And checking the stocking calculator on aqadvisor doesn't hurt :) Even if you don't listen, it's better to be knowledgeable and aware of what you're doing "wrong" so you understand the risks and how to control the situation.
 
Its probably the worst begginers guide to be honest like stated before putting a 10 inch oscar in a 10gal the best beginers guide is live aquaria or here dont start off with the wrong tank in the first place
 
Everyone keeps bringing up the 10 inch oscar in a 10 gallon tank. Does anyone actually think this? I've never heard of anyone wanting to do that before. Most of the time people think something like...three tetras and a guppy in a 10 gallon.
 
Arrowana in a 40g as well you go off there turning circle as well like if you got a 3ft arrowana in a 6ft tank thats only 2ft wide it still wont work also how active the fish is plays alot into it a 20 gal for a molly really isnt enough as they are active
 
Everyone keeps bringing up the 10 inch oscar in a 10 gallon tank. Does anyone actually think this? I've never heard of anyone wanting to do that before. Most of the time people think something like...three tetras and a guppy in a 10 gallon.

My local petsmart recomended a 2.5 gallon for a 2.5 inch german blue ram.
 
Yes im not doing the neon tetra bowl or a 10" Oscar in a 10 gallon because I know that's jus plain stupid. Different fish require different sized tanks. I just got a new 20 gallon tank. It will be heavily planted with tropical community fish and I just didn't wanna wanna over load the bio load...
 
Everyone keeps bringing up the 10 inch oscar in a 10 gallon tank. Does anyone actually think this? I've never heard of anyone wanting to do that before. Most of the time people think something like...three tetras and a guppy in a 10 gallon.

I don't know if they actually think it but I've seen people put smaller oscars in a 10-20 gallon tanks before. My friend has a oscar in a 25 gallon tank with a sun catfish. She's going to be looking for a 55 gallon for them but I think whatever damage she's done by keeping him in that small tank and not doing regular water changes is going to shorten his/her life. Poor thing has gotten hole in the head a few times and now gets cloudy eyes at random. :(
 
1 inch/gallon = almost true. This can work for some species.

It really depends on the fish species, tap water quality, filtration, planted tank or not, tank size, etc.

The best is to add fishs progressively and see how the filter handle the bioload.
Never do this rule with goldfishs.
 
This rule can apply with fish that max out at 1"-2". so yes in a 20 gallon you could have 20 1" fish (in general).

By adding plants you cant add more fish because plants take up swimming space and reduce the amount of gallons of water in the tanks. If you have a 20 gallon tank and half of it is plants then you really have 10 gallons. That is not taking into account substrate and other decor.
 
This rule can apply with fish that max out at 1"-2". so yes in a 20 gallon you could have 20 1" fish (in general).

By adding plants you cant add more fish because plants take up swimming space and reduce the amount of gallons of water in the tanks. If you have a 20 gallon tank and half of it is plants then you really have 10 gallons. That is not taking into account substrate and other decor.

If I may. The 1inch/1 gallon rule does not apply even to 1-2 inch fish as some are dirtier than others and a 1 inch fish still doesnt merit a 1 gallon tank. You wouldnt put 10 guppies in a 20 gallon probably. Well I guess you could but...
Also plants do allow you to have a higher bioload but reduces swimming spacem
 
This rule can apply with fish that max out at 1"-2". so yes in a 20 gallon you could have 20 1" fish (in general).

By adding plants you cant add more fish because plants take up swimming space and reduce the amount of gallons of water in the tanks. If you have a 20 gallon tank and half of it is plants then you really have 10 gallons. That is not taking into account substrate and other decor.

It would take an absolute boatload of plants to displace 10 gallons of water. I get what you're saying about a planted tank having decreased swim space but in terms of bio load (which I assume is the root of the 1"/gal rule) the water displaced would be negligible.
 
Fish can go into the plants, that's good hiding space, so it reduce the stress

Agree. My tank is by no means "heavily planted", but I do have 7 good sized plants and only one, a dense watersprite, seems as though it would realistically decrease and even then I've seen neons venture in there a few times.
 
It's an ok beginners guide in the sense that beginners don't have any idea how many fish to put in their tank so something is better than nothing.

Also beginners don't tend to buy oscars. Beginners tanks are usually 10-20 gallons and beginners fish usually consist of small species such as tetra rasbora guppies etc

So in that small respect I don't think it's actually as horrendous as people make out. I used it and if anything it ensured I was understocked which we all know is better than being overstocked. As you progress you learn how far you can push the limits. You learn more about different fish etc.

I would agree that if nitrates are at a level that require you to do more than 1 water change a week I would reduce the bioload. Plants do absorb some nitrates but not as much as you think. I don't think you should use any excuse to do less water changes.

Plants definitely help but it's water quality filtration and aquarium upkeep that enable you to push the limits. Pushing the limits is something we probably shouldn't do but we are all guilty of doing it at some point. Keep on top of your water quality. changing water cleaning the filter media in tank water and vacuuming the gravel will help keep nitrates lower.
 
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