PrettyFishies
Aquarium Advice Addict
I'm converting a brackish tank into a cichlid tank. I'm curious to know how many small, medium and large fish I can keep in 29 gallons.
TIA
TIA
How many fish in a 29g tank?
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odessadude
Aquarium Advice Activist
Let me start this by saying ten gallons of water per fish minimum. If you are going out and buying a couple of goldfish, they will grow too quickly with proper care to make it worthwhile to gradually move them to bigger tanks as they get bigger. Just start out with ten gallons per fish.
That said, there are situations where you might need to violate this rule. Raising a spawn of goldfish, for example, where you have lots of rapidly growing fish and will need to use multiple containers. In general the issue is dilution of waste products; you want to provide a stable clean environment for the fish, which means enough volume of water to sufficiently dilute the waste products between changes. This means that estimating how many fish you can keep in a given volume becomes a task of estimating how much waste they will put out.
My theory, which is loosely born out by a mathematical formula used in aquaculture, is that the waste output from a given fish is proportional to its surface area. Rather than its length or volume. What is the significance of this, if it is true? Two things:
Why, intuitively, would I believe that the waste output of a goldfish is proportional to its surface area? My reasoning is that the waste output should be proportional to the amount of food metabolized, and that this, in turn, should be a function of the surface area of the digestive tract. Which I would think would grow proportionally with the fish and be proportional to the fish's surface area. Whew! This all may be a bit loopy, especially if the metabolic rate of the fish changes significantly with size.
That said, there are situations where you might need to violate this rule. Raising a spawn of goldfish, for example, where you have lots of rapidly growing fish and will need to use multiple containers. In general the issue is dilution of waste products; you want to provide a stable clean environment for the fish, which means enough volume of water to sufficiently dilute the waste products between changes. This means that estimating how many fish you can keep in a given volume becomes a task of estimating how much waste they will put out.
My theory, which is loosely born out by a mathematical formula used in aquaculture, is that the waste output from a given fish is proportional to its surface area. Rather than its length or volume. What is the significance of this, if it is true? Two things:
- Using an "inches-of-fish-per-gallon" rule (favored by the pet trade) will lead to unnecessarily conservative estimates of the fish capacity of a tank.
- Using a "weight-of-fish-per-gallon" rule (used in aquaculture) will lead to underestimating the volume of water needed, either initially or as the fish grow.
Why, intuitively, would I believe that the waste output of a goldfish is proportional to its surface area? My reasoning is that the waste output should be proportional to the amount of food metabolized, and that this, in turn, should be a function of the surface area of the digestive tract. Which I would think would grow proportionally with the fish and be proportional to the fish's surface area. Whew! This all may be a bit loopy, especially if the metabolic rate of the fish changes significantly with size.
Where does this leave us? Well, you can take the surface area of a fish as being roughly a function of the square of its length (assuming that the shape of the fish maintains about the same proportions as it grows). Using this fact, and saying that a four inch long fish needs ten gallons of water, we can work backwards to estimate how many fish of shorter length that same ten gallons could hold. The following table shows example figures for constant length, constant surface area (my favorite), and constant mass:
LENGTH (in.) # of FISH (Length) # of FISH (Area) # of FISH (Mass) 0.5 8 64 512 1 4 16 64 1.5 2.6 7 19 2 2 4 8 2.5 1.6 2.6 4.1 3 1.3 1.8 2.4 3.5 1.1 1.3 1.5 4 1 1 1
Remember that this is all speculation. As a closing point, note that the amount of surface area is as important as the volume of a container. Goldfish need a lot of oxygen and most of this comes from air-water exchange at the tank surface. In general, I would recommend favoring squat-ish tanks as opposed to tall ones
odessadude
Aquarium Advice Activist
Well the cut and paste didn't work like I thought it would so try this link.
http://www.geocities.com/Tokyo/4468/howmany.html
http://www.geocities.com/Tokyo/4468/howmany.html
OP
OP
PrettyFishies
Aquarium Advice Addict
Do you believe that using a wet/dry bio wheel filter provides more efficient filtration and thus provides more flexibility with stocking rules?
JustOneMore20
Algae Fighter
What kind of cichlids were you looking at? I would skip those from Lake Malawi. You could get some Tanganyikans though. A pair of Julidochromis, some shelldwellers, and maybe a Calvus would work. Otherwise, you have the options of Dwarf Cichlids in a community or Keyholes. You might could have a pair of Firemouths in there with maybe a school of something.
Be more specific.
Be more specific.
odessadude
Aquarium Advice Activist
I guess scientifically you could get by with more fish, but the fish will not show very well in a packed tank. You want the ones that school to school together and if you have a bunch of fish in these they won't look good.
http://www.aquariumadvice.com/gallery/showimage.php?i=12184&catid=searchresults&searchid=17
http://www.aquariumadvice.com/gallery/showimage.php?i=12189&c=searchresults&searchid=17
The above pics show a 135 gallon tank both sides with a 75 gallon sump. These fish school really well and if I had a bunch of different species in there they would not school well.
http://www.aquariumadvice.com/gallery/showimage.php?i=12184&catid=searchresults&searchid=17
http://www.aquariumadvice.com/gallery/showimage.php?i=12189&c=searchresults&searchid=17
The above pics show a 135 gallon tank both sides with a 75 gallon sump. These fish school really well and if I had a bunch of different species in there they would not school well.
OP
OP
PrettyFishies
Aquarium Advice Addict
Ok. So what would you reccomend? I like the Mbunas and I'm also considering Tanganyikans. But I'm new to cichlids and don't know which work well. Ideally, I'd like one school of small (dwarf) species and like 3 to 4 individuals.
odessadude
Aquarium Advice Activist
OK the Mbuna's need a minimum of 60 gallons PH between 7-8.5 so you have to rule these out.
The Tanganyika's should be in a tank around 40 gallons.
How about LARGER TANK?
The Tanganyika's should be in a tank around 40 gallons.
How about LARGER TANK?
JustOneMore20
Algae Fighter
There are some Tanganyikans that will work in a 29g. You won't have alot of fish though, since most need a larger tank.
My suggestion, if you're set on Africans is this:
1 pair of Julidochromis (rock dwellers)
8 Neolamprologus multifasciatus (shell dwellers)
Maybe some Danios for dither fish.....or not
Or you could replace the Multies with a trio of L. occellatus, L. stappersi, or 2 pairs of N. Brevis.
The Multies will breed for you and build the colony up more. The Julies may breed as well.
If you want more fish than that or prefer color over personality, get a pair of Apistos and maybe a school of tetras or rasboras and make it a community.
Most Malawians need a 4ft tank.....3ft at the very least and that would not allow you many choices.
My suggestion, if you're set on Africans is this:
1 pair of Julidochromis (rock dwellers)
8 Neolamprologus multifasciatus (shell dwellers)
Maybe some Danios for dither fish.....or not
Or you could replace the Multies with a trio of L. occellatus, L. stappersi, or 2 pairs of N. Brevis.
The Multies will breed for you and build the colony up more. The Julies may breed as well.
If you want more fish than that or prefer color over personality, get a pair of Apistos and maybe a school of tetras or rasboras and make it a community.
Most Malawians need a 4ft tank.....3ft at the very least and that would not allow you many choices.
Fishyfanatic
Aquarium Advice Addict
Mbuna's are definitely out unless you have a 55 gal tank. Some keep them in smaller tanks but I wouldn't. And as long as you are not keeping wild caught species, don't worry about the pH.
The shellies and Julies are a good choice for a tank of that size.
The shellies and Julies are a good choice for a tank of that size.
OP
OP
PrettyFishies
Aquarium Advice Addict
Thanks so much. I was having trouble narrowing down the species that comprised "shellies." This helps tremendously. I think I o know which Julies I want, but what's the best way to get a M-F pair? My LFS is knowledgeable, but how difficult is it to sex them?
Next question: Setup
I plan to empty my tank and discard the gravel, then refill and decorate with rocks and shells (and rock backdrop). My qustion is cycling. I have an emperor bio-wheel filter. I use the fishless cycling method. Will this just rebuild the appropriate bacteria when I cycle? Or, will the existing bacteria on the bio wheel pose a problem since it was a brackish water before? Do I need a clean bio-wheel?
Is it neccesary to have trace elements added for these fish? What about salt mix? Anything else neccesary in terms of additives?
If I want to add plants (Vals, Anubias,etc.) would they be compatible witht he fish? Should I add those first or does it matter?
Next question: Setup
I plan to empty my tank and discard the gravel, then refill and decorate with rocks and shells (and rock backdrop). My qustion is cycling. I have an emperor bio-wheel filter. I use the fishless cycling method. Will this just rebuild the appropriate bacteria when I cycle? Or, will the existing bacteria on the bio wheel pose a problem since it was a brackish water before? Do I need a clean bio-wheel?
Is it neccesary to have trace elements added for these fish? What about salt mix? Anything else neccesary in terms of additives?
If I want to add plants (Vals, Anubias,etc.) would they be compatible witht he fish? Should I add those first or does it matter?
Last edited:
ok if you are going to go with shell dwellers you will want sand . if you want a good filtre go with an aquaclear and use a bag and fill it with coral chunks and bio rings . the coral and if you cannot get coral use shell chunks . as per plants there are some plants i have read that people use with shell dwellers. not sure wich kind. for a 29g ocelletus would be great or multifaciatus is another good choice. julies get a little teratorial so a small tank like that would not be that great.
JustOneMore20
Algae Fighter
I'm not certain, but you could probably use the same filter. I suggest filling the tank up with freshwater (after switching to sand) and running the filter for a few days in freshwater, doing some small water changes. Put some flakes or some kind of food in the water during this time to preserve the bacteria. I'm not sure this will work, but to me it seems fine to dilute the brackish water back into fresh like this, while still preserving the bacteria. Surely the bacteria would be the same and survive the transition to freshwater.
As for the choice of shelldwellers, that depends on what you want for the tank.
If you want a large-ish group of them, your best choice is going to be Multies. Occellatus and Stappersi are aggressive, so you'd be limited to a trio of either of them. Brevis pair up, so you should only have 2 pairs in a 29g (with alot of shells).
Some Multi fry may get eaten by the Julies, but they breed pretty readily, so you'd have a colony with them (more than one generation).
Similis look like Multies but they are a tad bigger and a tad more aggressive. I think you'd be limited with them as well in a 29g.
As for the choice of shelldwellers, that depends on what you want for the tank.
If you want a large-ish group of them, your best choice is going to be Multies. Occellatus and Stappersi are aggressive, so you'd be limited to a trio of either of them. Brevis pair up, so you should only have 2 pairs in a 29g (with alot of shells).
Some Multi fry may get eaten by the Julies, but they breed pretty readily, so you'd have a colony with them (more than one generation).
Similis look like Multies but they are a tad bigger and a tad more aggressive. I think you'd be limited with them as well in a 29g.
OP
OP
PrettyFishies
Aquarium Advice Addict
JustOneMore20
Algae Fighter
Yes, I'd take the water out. Do you have any freshwater tanks? If so, you could rinse the filter media in some cycled fw, just to rinse the salt off. Then run the filter on the new tank, but add in some fish food to provide an ammonia source while diluting the salt (or what is left of it) in the filter.
Definitely get a second opinion, as I've never had to do this yet. It seems like it would work to me though, but getting someone else's opinion would be good.
As far as rock, I've see big round river rock and slate both used in Tang tanks. You could even use lava or limestone rock. Really anything that you can get and make some caves/hiding spots from will work. I'd get some rock and stack it in one of the back corners of the tank.
Here is an example of the round rocks: http://www.thetropicaltank.co.uk/Tanks/Tankpics/tang-tank-old.jpg.
Different type of rock: http://www.aquahobby.com/tanks/img/307kevin1.jpg
Definitely get a second opinion, as I've never had to do this yet. It seems like it would work to me though, but getting someone else's opinion would be good.
As far as rock, I've see big round river rock and slate both used in Tang tanks. You could even use lava or limestone rock. Really anything that you can get and make some caves/hiding spots from will work. I'd get some rock and stack it in one of the back corners of the tank.
Here is an example of the round rocks: http://www.thetropicaltank.co.uk/Tanks/Tankpics/tang-tank-old.jpg.
Different type of rock: http://www.aquahobby.com/tanks/img/307kevin1.jpg
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