Question About Minimum Tank Sizes.

[wrightt3]

One thing I have always found confusing is that bigger fish have lower minimum tank size requirements relative to their size compared to smaller fish.
Let me explain:
 
Many would say that a 12 inch cichlid such as an oscar would need a minimum of 4x2x2ft (just under 120 gallons) Some would even say 75 gallons is acceptable. This would mean that the tank needs to be 4 times as long as the fish and 2 times as wide as the fish.
 
A smaller and far more peaceful species such as a ram however would apparently need a much larger tank relative to its size. Many on this forum would be disgusted if I said that I was going to keep a ram in a 15 gallon despite it being 8 times as long and 4 times as wide as the fish!?
 
I've had people saying my 15 is too small to keep neons despite it being 20 times as long as the fish when it is seemingly acceptable to keep bala sharks in 8ft tanks?
 
In a nutshell, why is this?

 

[ky*weremiej]

Good question!

The way I see it is, if your water is in good condition and you don't have any territorial issues then only you are the judge of your tanks, that's only the case if you work within reason for instance 8 angels would not be happy In a 10 gallon.

 

[baker360360]

I think it's to do with how active the breed is an Oscar would be happy sitting there slowly turning at each end where as groups of neons like to dart around all day long.

 

[Elrohirthehasty]

I'd say you could totally keep 12 neons in a 15 gallon tank, for what it's worth.

 

[Electric Warrior]

It's because it all depends on the fish I think. I think the example of rams that you gave is due to the fact that they can be really territorial when spawning, therefore they need s tank with quite a large footprint as they often claim a territory that spreads out quit a bit from their cave, etc. Neons, like most tetras need quite a lot of open swimming space, as they are a shoaling species. A small tank equals less open space or length to swim. In theory then, you could keep some tetras in a very long, but narrow shaped tank, which would mean less gallons, but there aren't really tanks made in odd shapes such as this.

 

[ky*weremiej]

This is a random subject, but its defo got my attention

 

[Wills]

I think the one thing is that bigger fish out strip supply of bigger tanks... as the species get bigger we end up working on minimums as not many people can provide more. Where as with smaller fish you can push up the minimum quite easily to suggest the bigger tank which is quite attainable but if you said that a minimum for an Oscar was a 120g not a 75g its just impossible for a lot of people to afford these or buy them. Where as an Oscar alone in a 75g can work great, especially as a wet pet or with something suitable. It also helps to prevent people getting a 55 and saying oh yeah Ill get the 120g soon... a 75g and a 55g are about as easy to find at about the same price. But the kit that often comes with the 75 is more suited to the bigger fish.
 
Then with the Bala Sharks, an 8 foot tank is the best of a bad situation, Bala Sharks are a migratory swarming fish to them an 8 foot tank is nothing really... But there are so many around that an 8 foot tank is a better option than a 4 foot tank and a much better option than... well I wont even suggest it but you can see what I mean. I think the same goes for a lot of fish really. We as a hobby cant provide the best homes for these fish but we can make them comfortable, feed them well and safe etc. And their ideal space is not attainable so it is a case of working on minimums.
 
The concepts and ideas of how to keep fish in our tanks is all just a group of experiences crossing and resulting in concepts of what a minimum is and what a good standard is. So for example the way a 75g came up as a good number for an Oscar is probably - too many people had them cause problems in a 55g or smaller - it happens with a lot of fish, Oscars are a good example though as they can cause a lot of issues, waste and water quality plus aggression and potential to eat some tank mates so working out a rule is quite easy and happened quickly because so many people were talking about it and warning others of what not to do. And it makes sense to see the minimum as the minimum because that is the point where success rates go up and up, so it makes sense to follow this even if you didnt post the original question. Similar for Angels, for me the bare minimum is 125 litres as long as the tank is 18 inches tall which means they dont graze / snap their ventral fins and suffer infections, fungus etc etc and 125 litres works as a minimum for length to provide the length and flow for the slow moving, dense vegetation dwelling fish to live.
 
But then it puts on a question of the smaller fish that what we should be providing larger than minimums for them to provide the best possible environment as possible.
 
Then there is a whole question of a "mob mentality" of a forum, by which I mean in the 4? years I have been a member here the minimum tank sizes and "inch" per gallon rules go up and down all the time it just depends on the members that are most active at any one time. So for example if your a member with the same tank and same fish for 3 years I could easily imagine your stocking would be judged as - understocked, stocked and overstocked in that time period...
 
In the case of the Neons in a 15g - it is probably okay to have them in there but I am a huge fan of the concept of alternatives and this is one of the classic situations - Green Neon Tetras, half the size of a normal Neon Tetra but ultimately a very similar, very attractive fish a much better life in a 15g tank for these fish more swimming to size ratio, opportunity for a bigger school etc.
 
If you research and read and look you can always find alternatives for colour, shape, personality, behaviour etc its just finding the right one.
 
So lets start up at a Columbian Tetra - bright blue with red fins gets to the size of a Digestive, need something smaller? Cardinal Tetra, different shape same colours still a reasonable size, need smaller still? Neon Tetra, need smaller still Green Neon Tetra? 4 species of fish that fill a very very similar (if not the same) niche - Blue and Red, schooling fish, South American. Yet you cover tank mates for a huge spectrum of fish, from big cichlids and minor predators and then you have fish that will fit into small tanks, suitably away from the former mentioned as well.
 
Just a few ramblings - hope it makes sense.
 
Wills

 

[eaglesaquarium]

As stated its not just about 'size' its also about behavior. The examples given above would be appropriate.
 
 
I'd add, I'm not a fan of bala sharks in the hobby, for the reason you give.  They are actually VERY ACTIVE and HUGE.  I think they should be in nothing smaller than at least a 12 foot tank, but they just don't exist!
 
Zebra danios are very small fish, but I recommend them at least 4 foot tanks, but a 5 or even 6 would be better.  Why?  Because of their active swimming nature.

 

[fluttermoth]

Good post, Wills; I just have one quibble; I don't think green neons are much smaller than the normals. I've had my shoal of greens for about three years now, and I would say they have the same adult size.

 

[Wills]

Good post, Wills; I just have one quibble; I don't think green neons are much smaller than the normals. I've had my shoal of greens for about three years now, and I would say they have the same adult size.

 
 
hmmm interesting - brings up an other question I didnt pose about accuracy of maximum sizes in most fish - for example if a supreme being were keeping us as pets would we be listed as a max height of something like 7 foot 2... I remember an old member on here had an Oscar that was 16 inches and just generally huge where as some other members had the same age (roughly) oscar and it was still just over the 12 inch mark and not as tall or thick. The other thing is as well, perhaps Neons are a good example here - mass breeding, bringing down the max size through genetics? I dont know just a thought...
 
Wills

 

[eaglesaquarium]

Max size would be 8 feet 11.1 inches.   (Robert Wadlow)

 

[wrightt3]

Yeah, I see where your coming from. It is affordable to give a small fish an appropriate home but it is not affordable for a larger fish but I still think its fairly hypocritical.
Thanks for the replies though, it was quite the read

 I think I've started an interesting debate here.

 

[eaglesaquarium]

Hypocritical?  Perhaps a bit harsh of a term.
 
 
I think the word you want is 'unfair'.   In other words, certain large fish shouldn't be a part of the hobby, because its just not feasible that they can be appropriately housed.
 
 
Kind of like a blue whale, a humpback whale, etc. can't be kept in aquariums because, well... they just are too blasted big.  Humpbacks naturally swim (at a minimum) from one pole to the equator on a regular basis. 
 
Personally, I like small fish, because they can easily be appropriately housed, not so with the 'tank busters'.  Just my own opinion.

 

[wrightt3]

Hypocritical?  Perhaps a bit harsh of a term.
 
 
I think the word you want is 'unfair'.   In other words, certain large fish shouldn't be a part of the hobby, because its just not feasible that they can be appropriately housed.

I'd say it's fairly hypocritical if someone's saying that someone else can't keep a certain fish in a certain tank but then go on to recommend a bigger fish for a tank that is proportionally smaller. (that is merely an example and is not aimed at anyone)
But yes, I agree with you 100%
Whilst larger, predatory fish are debatably more interesting than common community fish, I'd say that anything above 12 inches isn't really suitable for all but the largest of aquariums. (6ft+)

 

[eaglesaquarium]

But, again, its not just about the proportion of size of fish to size of tank.