Disputable Disputes…..

[Curiosity101]

Yes... because all the water changes in the world wouldn't keep two large cichlids together in a small tank. Or....perfect example is that you get 2 fully grown RTBS in a 20l tank together...all the water changes in the world wouldn't stop those two fish from fighting until one died. But if you gave them the proper sized tank to allow them to set-up the correct sized territories then you wouldn't have that problem.

 

[Curiosity101]

If you mean say... would I say keeping 3 x The normal level of bioload in a tank is ok if the person was willing to up the frequency of water changes to 3x the frequency and probably a slight increase in volume then yes.
If it were a shoaling fish that will be positively impacted by the increase in bioload then I'd definitely say it was a fine idea.

 

[Ludwig Venter]

OK Curiosity... I hear what you are saying, but is this a reflection on the Personality of the fish... (being territorially aggressive).... the size of the fish.... or is the direct issue to do with the number of water changes which is under scrutiny here???... (in response to Krib's statement)

 

[Curiosity101]

I'm just trying to demonstrate that although it's be nice to summarise, you can't.

For a fish that is positively impacted by an increase in numbers but that leads to a tank being 'overstocked' so long as the person isn't a new fish keeper and is willing to put on the extra filtration and do the additional water changes then I wouldn't have an issue with it.

But just to increase filtration and water changes to add some extra fish (random fish... say new species into a community tank). I would say is wrong, because the density isn't just about the bioload. It's about the other fish that have to then share the space with lots more species.

 

[kribensis12]

and it never plays a factor in what fish I want to keep.

The main question here Kribs... is on how many to keep and not so much on what to keep..... Saying (as you do) that you do many water changes.... would that have an effect of the number of fish you keep (in your opinion)??

Yes, because the fish is not happy if it can't even turn around in the tank. Now, just because I do a lot of water changes does not mean that I will throw 30 loaches into a 20 g tank because the water will still be clean. I factor in every option you gave, but compatibility always weighs heavily on me.

 

[Ludwig Venter]

and it never plays a factor in what fish I want to keep.

The main question here Kribs... is on how many to keep and not so much on what to keep..... Saying (as you do) that you do many water changes.... would that have an effect of the number of fish you keep (in your opinion)??

Yes, because the fish is not happy if it can't even turn around in the tank. Now, just because I do a lot of water changes does not mean that I will throw 30 loaches into a 20 g tank because the water will still be clean. I factor in every option you gave, but compatibility always weighs heavily on me.

So... In effect, you are saying that the size of the fish is the deciding factor...."Yes, because the fish is not happy if it can't even turn around in the tank"....

I reitterate... Say for instance, we are talking Guppies.... In a 20 Gallon... If I keep 20 Guppies in there, with a 3 monthly water change.... Do you think I can put 40 in there if I do a weekly water change???

 

[Tolak]

I'll stick to what I've always said; stocking is part science, part art. How do you quantify art?

 

[fett999]

I voted for amount of water changes personally, but this is as has been said by others only a part of the issue.
The reason I voted for this is because, as a slightly experienced fishkeeper I know about fish compatability, as most with experience will do at least to a degree.
This is something that I would advise someone to do if they know something about fish and full grown sizes. For instance, most people with experience know that a silver/bala shark is gonna grow to about a foot long, is extremely active and really needs to be in a fair size group and so won't even think about putting a single one in a 20l tank.
If you are talking to a total newbie though I believe that, in a better safe than sorry frame of mind, I would usually tell them to keep to the 1cm per litre /1 inch per gallon rule.
This is an extremely basic and simplified rule, however it is a very safe point for newby's to start from.
It makes any mistakes they make, which lets be honest almost all of us did when we started, less likely to cause a complete breakdown in the tank, resulting in the death of all the fish and a new fishkeeper deciding that the hobby isn't for them.
I started out with that rule and have ssince gained enough knowledge to feel confidant moving on from it. If I had started out using the water change rule, which I feel is a more accurate one ( when used in conjunction with other rules like compatability, etc) then not only would I probably havee had more problems to begin with and decided that fishkeeping wasn't for me, but I may also have gotten really annoyed with constant water changes and given up before the hobby had really grabed me.

To sum up, I think that for experienced keepers you can use the water change rule, in conjuction with others, but for a newby the much simpler rule is the best jumping on point you can give them, whilst giving them as much good info as possible so that in time they can start to make up there own minds when they feel more confidant.

 

[BethK]

See, i only really have experience with bettas and imo, as long as your tank is planted well, hiding places, good filtration, heater, then I think the 'stocking rule' can be put aside but i would say research and experience plays a key in that. (as long as they are not in anything less than a 30ltr, min. if 5 girls in that)

but bigger fish, i would say tank size plays a major key factor.

 

[rdp50734]

For me all the options need to be taken into account but I voted, its how the fish looks in there! ie a 16" channa pluero needs a 300l ish tank. With a large footprint. They're quite delicate so water quality plays a part. Obviously a 300l tank is 75 gallons ish for a 16" fish? inch per gallon goes out the window! If you have a bad fish then not many tankmates!
A 16" fish in a 4" tank will look quite full but it has to be in the eyes of the owner.
I read in a recent thread that you could not keep discus in a 180l tank without even considering the current size of the fish or the fact that the OP had stated there was an upgrade planned! I had 8 in a 200l and they were fine but they were 3-3.5" so tank size wasn't a factor until they started getting bigger then the pack would be thinned out to suit the sized tanks I have.
In my opinion we can't give a rule just guidance from our own experiences. An example of this was that a Jack Dempsey cichlid was super aggressive. From my experience and others that posted on the thread, the ones we kept were quite mellow and shy. I think experience and guidance should be an option!
Ps this is just my opinion and is not intended to troll or flame the people who were/are involved in any of the examples I have mentioned.

 

[OldMan47]

Some of the many factors involved in how many fish you can keep are intraspecific and interspecific aggression, ultimate fish size, willingness to do enough water changes to remove biological contamination such as nitrates. Things that have no bearing on how many fish can actually be in any decently outfitted tank are filter size and filter flow, strength of water circulation and ignorance about the fish's needs as expressed by "just chuck them in".

 

[star4]

Great Ludwig, I had to think
I plumped for "Do you think the species of the fish influences the number you can keep"

The reason why I chose this one is there are certain fish that cannot be kept in large numbers together eg male betta, and others that do better in large numbers eg malawi. Our first tank started off with about 15 guppies, male and female which soon expanded to over 50, then problems started, got another tank and another!! Now I have moved over to ca/sa cichlids and admit that a couple of my tanks do break the stocking rules of thumb by being overstocked, however the aggression levels in these tanks are minimal! and all the fish use the whole tank for swimming in rather than hiding away behind decor. It is not something I would recommend, however it has worked for me, but the maintanance on these tanks is heavy with twice weekly water changes and cleaning out the filter monthy.

Personally I dont think there can be one specific rule to keeping a tank happy and healthy, keen observation of your fishes behavior is also a key factor, I dont just mean they are eating. Watching their body language towards each other, their colouration etc.

I admit it makes me cringe when someone new joins the forum and they list their fish and they get jumped on with "your tanks overstocked".

 

[Twinklecaz]

I agree, someone told me when I was new that 1 inch of fish to every 2-3 gallons was the rule which I think is just slightly OTT lol. You get a fair bit of that on here I find.

I do think thought that people just like to help and stocking is something that most people have an understanding of so when someone asks, everyone can and usually does answer. Whereas the science of the fishless cycle stumps most people so you get less answers.....if that makes sense.