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I am right at the inch per gallon rule of thumb now...I just took some measurements of my tank because I wanted the exact dimensions when people would ask. The person that gave the tank to me said it was a 29 gallon tall...I shouldn't have taken his word for it...turns out it is a odd ball 26 gallon tall!

I haven't even heard of a 26 gallon tall. Anyway, here is my stock list, please tell me if it is over crowded.

1 dwarf gourami
1 bolivian ram
7 lemon tetras
3 cherry barbs
2 corys (bronze and peppered)

I know I am going to take some flack for only having two corys, but there is something in the water here that they dont like. I have had two batches of 7 bronze corys and 1 batch of peppereds...they would experience barbel erosion, then they would start hiding,not swimming,and stop eating. then they would get sick and unable to swim at all. I tried everything from differant substrate and ph's...the water DH was ok, a little soft, and ammonia and n3 levels were very low. I can't keep them alive, but the two I have left are the most active fish in my tank and seem very happy, so at the risk of killing more corys I am not adding any more to the pair.

Now, back to the overstocking issue. I have two aquaclear 50s(200gph max),a powerjet, and two airstones and I do a 30% water change a week.

I just added the gourami and two of the lemon tetras yesterday, I have been watching ammonia levels closely, I wouldn't have added the gourami if I had known I had a 26 gallon. So, should I take the gourami back or am I ok?

first thing, throw that rule out the window. but IMO, you should be ok there. i've told people, best be over filtered than under and with the water changes, that will help also.

i knew someone who had about 110 guppies in a 20g long, and she had two whisper 30s (i believe) and did weekly water changes. and she never had any problems.

Fish tanks are an expensive addiction

first thing, throw that rule out the window. but IMO, you should be ok there. i've told people, best be over filtered than under and with the water changes, that will help also.

I strongly disagree with you there. Even with heavy filteration and water changes, that doesnt mean the fish arn't cramped in there. In addition to that, just because you filter well doesn't mean your chemical balance won't get messed up. The 1" rule is a good rule (when used practically, i.e. no 10" fish in a 10gal, but 10 small fish, like galaxy rasboras are okay) This rule is there for a reason, not just a cookie cutter, it basically is there because fish need a certain amount of space to stay happy and healthy. ^^

REUN-
As far as your stocking goes, I think you arn't overstocked. I do think that the cories are a problum. have you tried to trade them in at an LFS? If you trade them in, that would open you up for a bottom feeder that may be less sensitive to your water conditions, perhaps a rubberlipped or bristlenose pleco?

Inky

I agree with monkeyboy , that inch rule was always complete rubbish of the worst type, responsible for both ridiculous overstocking and paranoid understocking- its good for nowt, and belongs firmly lodged in the annals of the ancient and inaccurate never be used again. It a poor replacement for observation and bioload calculation.

That tank is not overstocked, its about ok. Cories do better in higher numbers which you cant really push in that tank. I dont really see that there should be a water quality issue here though. There probably isnt one, and cories are not by any means the most sensitive species.Bronze cories in particular are almost bomb-proof compared to what would be called truly sensitive fish. They can take anything that ram can, and more besides.

The only vague problem is the orientation, most shoals prefer lengthways room over height, aside from that small gripe, everything is fine.

How on earth would a bn or a rubbernose plec need less room or have less impact on the bioload than a cory?

They wouldnt. It would make things worse. BN 's could represent their country for the amount of crap they produce ,it would easily double the burden on the tank that cories produce,being both much bigger , having an enormous appetite and a higher metabolic rate, and rubbernoses are more sensitive to water quality than cories any day of the week. Add to that the tank would no longer have an efficient scavenger and the water quality would get worse, not better.

yeah, I have grown attatched to the bronze as it was one of the first fish I had, and is now 4 years old...I really don't want to trade her in...

If the two corys camped out under the rocks all day and didn't move other than to eat, I would be worried, but they are probably the most active fish in my tank, and are always rummaging around or playing tag with eachother.

I had a BN pleco, but it was very agressive,hungry,and poo'd like no other fish I have ever had... I agree a single bn might be happier than my two corys, but I dont think the 26 tall can compensate for it.

I am not sure if I had bum luck with corys, or if there was disease or water quality issues, but I dont want to trade in some of my fish to try and get a school of 6 corys in a tank with this small amount of bottom space.

I am sure more swimming space would be appriciated by the fish, but they all seem quite content, as the ram and corys hang out in the lower 6" of the tank, the tetras from the 6" mark to the 18" mark, and the gourami hangs out at the surface of the tank at the 18"-20" mark.

I will be watching my nitrates very closely for the next couple of weeks, but I am hoping the overfiltering and water changes will compensate, even though I am right at that 1" per gallon rule.

Let me elaborate here on LHG's words.

The inch per gallon rule is a convenient shorthand that works with some fishes. But, it doesn't work with them ALL.

The ultimate measure of a fish's likely bioloading is biomass. While this is a quantitative measure that gives very good general agreement with the likely pollution output of a fish in terms of ammonia etc., it's an awkward measure to use for aquarium fishes - it's used in fish farms that farm food fishes because measuring the biomass of something the size of a large salmon is easy - you just pop it on a weighing machine and immediately get a good answer. Try doing that with Neon Tetras, on the other hand, and you run into severe problems - mostly due to the fact that the biomass of an individual Neon Tetra is tiny, and to measure that accurately you would need laboratory standard weighing equipment of the kind used in micro organic analysis in chemistry, and that's a piece of kit that would blow a $2,000 hole in your bank account in an instant. Then, of course, the same piece of kit that would allow you to assess the biomass of Neon Tetras accurately so that you could calculate their ammonia and faecal output (using some fairly involved equations I might add - how good are you with numerical approximation of partial differential equations?) would, unless it was a pretty special piece of kit, be next to useless for doing the same with Oscars, which are FAR bigger fishes.

You could try approximating this by working out how much volume the fish occupies, and making an assumption about density (namely that for a fish that remains suspended in mid water, it's average body density is the same as that of water) thus giving you some idea of the body mass indirectly (though less accurately). However, since mass is related to volume (the complications of tissue density calculations notwithstanding), this should tell you that a rule based upon a linear measure of fish length is going to be inadequate when the true ammonia and waste output is a function of biomass, which in turn is a function of body volume. For example, a juvenile Congo Tetra at 1 inch in length is going to have a specific body mass, call this value m for the moment - but once it grows to 2 inches in length, its mass is going to be a function of volume, and this will be eight times the volume (namely 2x2x2) that the fish possessed at a body length of 1 inch. Therefore the biomass has shot up from m to 8m.

This puts the Neon versus Oscar picture neatly into perspective. Assuming that the tissue densities of the two fishes are identical (not a robust assumption, I admit, but for the purposes of this comparison the final numbers will probably be out by no more than 1%), then a 1 inch Neon Tetra has a biomass of m, say, while a 12 inch Oscar has a biomass of - wait for it - (12x12x12)m = 1728m. Your 12 inch Oscar has over 1,700 times the biomass of the 1 inch Neon Tetra! So it should not be surprising in the light of this that the 12 inch Oscar is going to produce a LOT more ammonia and other waste than the Neon Tetra!

Of course, this picture is simplified greatly for another reason. Fishes with sedentary lifestyles will have a lower metabolic rate than active fishes. So, something like a Prehistoric Monster Fish, Thalassophryne amazonica, that spends most of its time lurking and waiting for food to come to it, will have a lower metabolic rate than a Bala Shark, Balantiocheilus melanopterus, that is actively swimming about the water all day pursuing food. So even if an individual of one species has the same biomass as an individual of the other, the metabolic rates are going to be considerably different, and their respective outputs different also - the Bala Sharks are going to produce a good deal more ammonia than the Prehistoric Monster Fish. So even discounting the need for swimming space simply because of the size and activity of the fish, the increased ammonia output due to high metabolic activity is going to dictate a large aquarium for the Bala Sharks even if one does not factor in the need to provide the fishes with space that doesn't leave them physically cramped.

Another factor that is going to complicate the picture is diet. Limnivorous Loricariids that chew wood as part of their feeding process, and which need wood in the diet to facilitate digestion, may not produce copious amounts of ammonia in comparison to, say, the Bala Sharks, because they're somewhat less active, but the faecal output from a wood eating Plec is going to be frightening to behold because only about 10% at most of the matter passing through the gut is actually digested - 90% of it goes straight out the back end. Herbivorous fishes are likely to produce a bigger volume of faecal matter than carnivorous ones, principally because cellulose is unlikely to be digestible by the fishes (and as far as I'm aware there are no ruminant fishes!) so Pacus are going to produce more faecal matter per unit of body mass than Oscars. Factor in the huge size of adult Pacus as well, and the bioloading that Pacus place upon a filtration system is colossal.

An interesting comparison was made by Practical Fishkeeping magazine with respect to body mass when they wrote a brief piece on a fish called Wallago attu, the Helicopter Catfish. This fish is NOT recommended for the home aquarium because it is a behemoth - an adult reaches SIX FEET in length - and in terms of body mass, Practical Fishkeeping cited that its body mass was equivalent to that of 45,000 Neon Tetras! That puts things nicely into perspective, doesn't it! If the one inch per gallon rule worked for ALL fishes, then the Helicopter Catfish would only be equivalent to 72 Neons ... but of course even a casual glance at an adult Helicopter Catfish puts that notion in the bin straight away ... incidentally, apart from its colossal adult size, the Helicopter Catfish is not recommended because it has a cavernous mouth, a propensity to bite its owner and a large one can take your hand off. A six foot specimen is capable of swallowing a Pekingese dog whole - that's more food in one go than 72 Neons will eat in a lifetime!

So, with regard to stocking, the questions that need to be asked are:

[1] Is the fish going to be large as an adult? If so, it's bioload is going to be correspondingly large, and should be planned for.

[2] Is the fish highly active (e.g., Bala shark, Tinfoil Barb). If so, the bioload is going to increase over and above basic mass because of increased metabolism, and should also be planned for.

[3] Is the fish primarily herbivorous, or with other dietary oddities that increase faecal output? If so, the bioload will increase yet again over and above basic mass, and should be planned for.

The practical upshot of all this is that Neons produce a tiny bioload individually, so in a 55 gallon you can have an impressive shoal of them, but one Oscar will outgrow the 55 in fairly short order, and the 55 will be useless as a long term home for Bala Sharks or Tinfoil Barbs. By the time you're looking at something like Acanthicus adonis, a juggernaut Plec that reaches 3 feet as an adult, you're looking at aquarium sizes that constitute civil engineering projects - 1,000 gallons is probably the minimum I'd recommend for long term housing of an Adonis Plec, and the filtration system that's going to need is almost industrial scale. If you're mad enough to try keeping a Helicopter Catfish, then my recommendation is that you start thinking about hiring a 50 ton excavator and digging a small lake for it, which you then cover over with its own housing - a hangar big enough to house a 30 seat turboprop airliner is the kind of building you're looking at here!

If all of this is beginning to sound as if stocking is a judgement call in many cases, then yes, you're right. Unless you're fortunate enough to be able to evalutate the biomass and the metabolic rates of your fishes quantitatively, and can plan with precision, you have to exercise judgement. So, for example, you could opt to stock conservatively with low-bioloading species to give you some room for manouevre, or you could opt for some higher bioloading fishes and be prepared to increase maintenance interventions (water changes etc.) to facilitate the higher bioloading fishes. Ultimately, what works is partly learned through experience until such times as researchers publish quantitative bioloading tables for our aquarium fishes, which I suspect is going to be a long way off in the future ...


Panda Catfish fan and keeper/breeder since Christmas 2002

Nice one cal! Good post!

I so wish I had the energy to write all that.lol

wow! that was quite the elaboration of the inch per gallon rule,lol.

I hope that with my current filtration the nitrogen stays down and I can keep them all

reun, just make sure to watch it closely to make sure and if it does, take action as soon as you can

Fish tanks are an expensive addiction

well, the powerjet filter I have is 55 GPH and injects air into the water and has a sponge element, and i have two 200gph over the back filters full of floss and sponges, so I am hoping this will compensate for the added stock.

so far no nitrogen spike, but it has only been a couple days...I am still watching the levels closely and I am about to do a 30% water change.

hey reun,just 1 thing that no one mentioned,ive always been told,that if you can detect ANY ammonia,its too much,it also says that in a few books i have also,unless it zero,its too much,maybe grab some buffer or some aaa blocks,or an ammonia gauge,ammonia is nasty stuff bro,even in small amounts, fish can still get stressed out,then you open then up to other things,being more likely to get sick,finrot,the list is endless.

ps.excellent post cal,as always well done

I think u r ok

Yup. I'm that crazy Twilight/animal/music girl

I understand what you are saying as far as the 1in rule goes. I am also trying to say that you shouldn't tell people to "throw it out the window" as it is a good basic tool for begenners to go by, and works on many fishes that are favorites to begenners. For example, a male betta gets to about 2 inches long, and should be keept in at least a two gallon. (Yes, smaller containers are often used and larger ones too, but lets not get into that right now) If you add anything to the tank, say a pair of cherry barbs, which if I am not mistaken get to be about 1.5in each (right?) that would make your min. tank requirement 5gal. See? But the rule doesnt apply to everything, example: A Common pleco would not be happy in a 12 gallon tank. ^^

I just hate people saying "don't use the one inch rule" because then begenners see it and say, "gee, that means I can put anything I want in the tank" I think it is wrong to give off this type of impression. Thats all I am saying.

AS FAR AS THE CORIES GO-

My point was that adding a school of the cories (uping the total number to 6+) per type bronze and peppered (total of min. 12 fish) would be a big overload on the bioload. Thats why I said that adding a BN or other smallerfish instead of the 2 cories would be better, since the cories really should be in a schools.

I just thought I'd clarify

Inky