Max # Of Fishes For 20 Gallon?

[driger8642]

Planing to get a 20 gallon for my nephew's room, was wondering what is the max number of fishes I can put in it. What I mean by that is, which kind of fishes I can put in there without overcrowding it. Already plan on putting 4 corys in there, no angelfish since I know they need their space, any species that can live in the 20 gal, are peaceful, and I can have many of them. I would love if there can be 2 or more species that I can put in there without overcrowding (if possible).
 
Pretty much want to have as many in the tank as I can without stressing them since my nephew is still young and for him it is quantity>quality
 
Thanks in advance

 

[hudsona85]

There are many possibilities to go with this. But to get to the root of the question becomes more questions. Do you know the water quality of the tap water? Soft? Hard? You can find this out by looking up your local water. This will help determine what kind of fish you can actually keep. Will this tank be easy to reach? What kind of cycle do you intend to do? IF you plan to have corys in there I would recommend having a sand substrate as they like to sift through to find food and would not damage the barbels. Might I add since you are thinking of having corys to have at least 6 since they do better in shoals. This should give you a good start of homework to narrow down the options you have for him. 

 

[r.w.girard]

There is no way to responsibly answer this question as any number of factors go into stocking an aquarium. Compatibility, temperature, pH, etc. as well as filtration all influence what fish can be stocked where. A small school of small rasboras [hengeli rasboras are vibrant and active and school very tightly but can be hard to find at the LFS] or small tetras could work with a centerpiece like a small gourami.They say corydoras should be kept in groups of at least 6 but I have never kept them so I will leave that to the experts. I would cruise through some of the aquarium journals and see what people have stocked in their 20g tanks. Also a 20L is different than a 20H in terms of stocking (for reasons of gaseous exchange).

 

[driger8642]

There are many possibilities to go with this. But to get to the root of the question becomes more questions. Do you know the water quality of the tap water? Soft? Hard? You can find this out by looking up your local water. This will help determine what kind of fish you can actually keep. Will this tank be easy to reach? What kind of cycle do you intend to do? IF you plan to have corys in there I would recommend having a sand substrate as they like to sift through to find food and would not damage the barbels. Might I add since you are thinking of having corys to have at least 6 since they do better in shoals. This should give you a good start of homework to narrow down the options you have for him. 

I tried the method stated here http/www.wikihow.com/Determine-if-You-Have-Hard-Waterand looks like the hardness is around 3 out of 10. I plan to do a fishless cycle, going to have a 20 gallon tall tank, 150 watt heater, tetra whisper 40 filter, sand substrate, fake plants, ornaments, wallpaper in the back. Going to use some water from my fully cycled tank to help with the beneficial bacteria. And the tank cannot be reached easily, at least for my nephew xD.
 

There is no way to responsibly answer this question as any number of factors go into stocking an aquarium. Compatibility, temperature, pH, etc. as well as filtration all influence what fish can be stocked where. A small school of small rasboras [hengeli rasboras are vibrant and active and school very tightly but can be hard to find at the LFS] or small tetras could work with a centerpiece like a small gourami.They say corydoras should be kept in groups of at least 6 but I have never kept them so I will leave that to the experts. I would cruise through some of the aquarium journals and see what people have stocked in their 20g tanks. Also a 20L is different than a 20H in terms of stocking (for reasons of gaseous exchange).

Not a bad idea with the rasboras, i hope the petco has them, also the tetra..... wouldn't 1 small gourami feel lonely or would it be okay? I would hate to stress out the poor fish. And yeah I guess I can get 6 corys instead of 4 thanks

 

[r.w.girard]

Harlequin rasboras are easily found - although somewhat larger than Hengeli rasboras - and you could go with a male-female pair of dwarf gouramis. Females might be hard to find at the local Petco and so a single male would be preferable. One of the problems of keeping multiple species of schooling fish is that it is hard to keep fully schools.
 
If you decide what kinds of fish you are interested in keeping, it would be easier to judge if something is reasonable or not.

 

[hudsona85]

 

There are many possibilities to go with this. But to get to the root of the question becomes more questions. Do you know the water quality of the tap water? Soft? Hard? You can find this out by looking up your local water. This will help determine what kind of fish you can actually keep. Will this tank be easy to reach? What kind of cycle do you intend to do? IF you plan to have corys in there I would recommend having a sand substrate as they like to sift through to find food and would not damage the barbels. Might I add since you are thinking of having corys to have at least 6 since they do better in shoals. This should give you a good start of homework to narrow down the options you have for him. 

I tried the method stated here http/www.wikihow.com/Determine-if-You-Have-Hard-Waterand looks like the hardness is around 3 out of 10. I plan to do a fishless cycle, going to have a 20 gallon tall tank, 150 watt heater, tetra whisper 40 filter, sand substrate, fake plants, ornaments, wallpaper in the back. Going to use some water from my fully cycled tank to help with the beneficial bacteria. And the tank cannot be reached easily, at least for my nephew xD.
 

There is no way to responsibly answer this question as any number of factors go into stocking an aquarium. Compatibility, temperature, pH, etc. as well as filtration all influence what fish can be stocked where. A small school of small rasboras [hengeli rasboras are vibrant and active and school very tightly but can be hard to find at the LFS] or small tetras could work with a centerpiece like a small gourami.They say corydoras should be kept in groups of at least 6 but I have never kept them so I will leave that to the experts. I would cruise through some of the aquarium journals and see what people have stocked in their 20g tanks. Also a 20L is different than a 20H in terms of stocking (for reasons of gaseous exchange).

Not a bad idea with the rasboras, i hope the petco has them, also the tetra..... wouldn't 1 small gourami feel lonely or would it be okay? I would hate to stress out the poor fish. And yeah I guess I can get 6 corys instead of 4 thanks

 

Based on this test that you tried you have mostly soft water. However, I don't know how much I would rely on this test. Sure fire way to make sure is to visit your local water supply website. I agree with r.w.girard. I would definitely look into some journals to get an idea as to what ideas would work. Dwarf Gouramis prefer to be by themselves as far as their own species. r.w.firard is also right when it comes to looking for female gouramis. Most LFS wont carry them due to the plain looks, and distributors needing them for breeding purposes.. You can do some research to find places online that will carry them if those are what you want.

 

[Ltygress]

Most LFS will also test water for you for free. Petsmart usually will.
 
Mom-and-pop LFS places MAY charge you a tiny bit like a dollar or two, but they are also the most knowledgable and won't give you BS answers like Petsmart would. "Oh it's a little high" to Petsmart may be 40ppm Nitrate, which is really high! (I'm also touting mom-and-pop places because my local one just GAVE me marine salt yesterday so I can try my hand at RAISING brine shrimp.)

 

[driger8642]

Thanks a lot guys, definately helpful insights. I will be taking a water sample to petco and see what they say.
 
 

Harlequin rasboras are easily found - although somewhat larger than Hengeli rasboras - and you could go with a male-female pair of dwarf gouramis. Females might be hard to find at the local Petco and so a single male would be preferable. One of the problems of keeping multiple species of schooling fish is that it is hard to keep fully schools.
 
If you decide what kinds of fish you are interested in keeping, it would be easier to judge if something is reasonable or not.

 Can you expand on "hard to keep fully schools". Do they die off or something? or you just cant have them fully schooled because you cant fit that many in a tank?
 
I plan on getting some Rasboras, tetras, and 1 Gouramis. Sounds okay for the tank or will it be over crowded?

 

[Byron]

I would not waste time having water tests at stores, except in an emergency.  The hardness of your tap water should be easily ascertained from your municipal water authority, usually this data is on their website.  You want to know the GH (general hardness), and also the KH (carbonate hardness, bicarbonate hardness or Alkalinity) as this serves to "buffer" the pH.  The pH also is worth knowing, though it is mainly the GH/KH that can seriously impact some fish depending upon the fish and the numbers.  The GH/KH tends not to change much, if at all, in an aquarium, unless you are specifically targeting it to raise/lower it.  So with inert sand and no calcareous rock, this should remain fairly stable at what comes out of the tap.
 
Gourami.  This name applies to many species, and very few are suitable for a 20g.  The Honey Gourami is probably your best bet, one male (males are more colourful) should be OK.  Some gourami are very territorial (males especially) but this species is usually safe.  I would avoid the Dwarf Gourami, they can be carriers of serious disease depending where they originate (the supplier, not the store) and they are not always friendly.  There is also the pygmy sparkling gourami, but we need to know water parameters before suggesting this species.  A group of three would be fine.  They are obviously much smaller and less "shjowy" so thinking of your son, perhaps the Honey would be better regardless of water.
 
Tetras, rasbora, and several other types of tropical fish are shoaling fish that must have a group.  Depending what species, you might be looking at 6-7 up to 10.  There are many species of tetra that are completely inappropriate in a 20g, so we need to be careful here.  Rasbora tend to be less of a problem, though species still differ.  The Hengeli is a lovely fish, and a group of 9-10 would be fine.  Again, I would want to know the water params first, as this species tends to be wild caught.
 
I';; very briefly pick up on the very pertinent comment that r.w.girard made about factors affecting compatibility.  Many fail to understand these, and success will only happen if one takes all of them into account.  While the fish maximum size is certainly important, this can be offset by other issues like water parameter preferences, temperament, numbers required, behaviours, water flow (from the filter), and the environment in terms of decor.  All species of fish have evolved to suit a very specific environment, and while some seem adaptable to at least some degree, many really are not long-term.  And we all want the long-term health and "happiness" of our fish to be the goal.  I or others can go into more detail when specific species are mentioned.
 
By the way, you mentioned using water to seed the bacteria...this will not do it.  Bacteria live on sticky surfaces called biofilms, and without using solid matter from an established tank, such as a filter, or media from the filter, or substrate, or decor items (wood, rock, etc), you won't seed the tank with nitrifying bacteria.  Aside from this, there is going to be "stuff" in the water that you really won't want to be adding to your aquarium anyway; pathogens of various sorts, pheromones/allomones, etc.
 
Byron.

 

[driger8642]

I would not waste time having water tests at stores, except in an emergency.  The hardness of your tap water should be easily ascertained from your municipal water authority, usually this data is on their website.  You want to know the GH (general hardness), and also the KH (carbonate hardness, bicarbonate hardness or Alkalinity) as this serves to "buffer" the pH.  The pH also is worth knowing, though it is mainly the GH/KH that can seriously impact some fish depending upon the fish and the numbers.  The GH/KH tends not to change much, if at all, in an aquarium, unless you are specifically targeting it to raise/lower it.  So with inert sand and no calcareous rock, this should remain fairly stable at what comes out of the tap.
 
Gourami.  This name applies to many species, and very few are suitable for a 20g.  The Honey Gourami is probably your best bet, one male (males are more colourful) should be OK.  Some gourami are very territorial (males especially) but this species is usually safe.  I would avoid the Dwarf Gourami, they can be carriers of serious disease depending where they originate (the supplier, not the store) and they are not always friendly.  There is also the pygmy sparkling gourami, but we need to know water parameters before suggesting this species.  A group of three would be fine.  They are obviously much smaller and less "shjowy" so thinking of your son, perhaps the Honey would be better regardless of water.
 
Tetras, rasbora, and several other types of tropical fish are shoaling fish that must have a group.  Depending what species, you might be looking at 6-7 up to 10.  There are many species of tetra that are completely inappropriate in a 20g, so we need to be careful here.  Rasbora tend to be less of a problem, though species still differ.  The Hengeli is a lovely fish, and a group of 9-10 would be fine.  Again, I would want to know the water params first, as this species tends to be wild caught.
 
I';; very briefly pick up on the very pertinent comment that r.w.girard made about factors affecting compatibility.  Many fail to understand these, and success will only happen if one takes all of them into account.  While the fish maximum size is certainly important, this can be offset by other issues like water parameter preferences, temperament, numbers required, behaviours, water flow (from the filter), and the environment in terms of decor.  All species of fish have evolved to suit a very specific environment, and while some seem adaptable to at least some degree, many really are not long-term.  And we all want the long-term health and "happiness" of our fish to be the goal.  I or others can go into more detail when specific species are mentioned.
 
By the way, you mentioned using water to seed the bacteria...this will not do it.  Bacteria live on sticky surfaces called biofilms, and without using solid matter from an established tank, such as a filter, or media from the filter, or substrate, or decor items (wood, rock, etc), you won't seed the tank with nitrifying bacteria.  Aside from this, there is going to be "stuff" in the water that you really won't want to be adding to your aquarium anyway; pathogens of various sorts, pheromones/allomones, etc.
 
Byron.

That was VERY informative Byron, thank you. I went to the website (New York) http/www.nyc.gov/html/dep/html/drinking_water/wsstate.shtmlbut I couldn't find anything on water hardness. I skimmed through it but no luck, and yeah thanks for the water advice, I didnt put any old water into the new tank, letting it cycle on its own with the filter and checking water quality. If you can, please look into the water hardness level for NYC since I cant seem to find anything on it, and depending on that suggestions on the type of fishes I can have are much appreciated Thanks once again ^^

 

[driger8642]

How is this for example?
 
6 peppered corys
2 Guppies
10 Neon Tetras (Research shows they are more peaceful than other species of tetra)
 
Not sure how accurate Advert for another forum removed can be but here it is....
Also it says that the ratio for than 1 guppy is Male to Female 1:2. any insight on that? Would 2 males really be a big problem? What about 2 females? Reason being I do not want any Fry ( at least for now ).
 
http/aqadvisor.com/AqAdvisor.php?AquTankName=&AquListBoxTank=Choose&AquTankLength=24&AquTankDepth=12&AquTankHeight=16&AquListBoxFilter=Tetra+Whisper+40&AquTextFilterRate=40+&AquListBoxFilter2=Choose&AquTextFilterRate2=N%2FA+&AquFilterString=tetra&AquListBoxChooser=Neon+Tetra+%28Paracheirodon+innesi%29&AquTextBoxQuantity=10&FormSubmit=Add+%3E&AquTextBoxRemoveQuantity=&AlreadySelected=200909300161%3A6%3A%3A%2C200909300093%3A2%3A%3A&FilterMode=Display+all+species&AqTempUnit=F&AqVolUnit=gUS&AqLengthUnit=inch&AqSortType=cname&FilterQuantity=2&AqJuvMode=&AqSpeciesWindowSize=short&AqSearchMode=simple
 
I know the tank capacity is 105% shown which im guess is slightly overcrowded. Is that fine? If only 1 guppy, it will go below 100 and if i decrease 10 neon tetras to 6 then it will also go down to around 95% i beleive. I would prefer reducing the tetra than the guppy since I dont want the Guppy to feel alone
 
Sounds like a good setup?
 
Ofc I will be doing a fishlesscycle before adding any fish, also after finding out the water hardness level as stated in the comment above ^^
 
 
 
**************************************
 
Only lets me edit the latest post (i think) so this is for Byron
 
I called 311 for NYC and so I can only get the hardness level (over the phone) on tuesday, monday being coloumbus day so its a holiday. If you can somehow find the hardness level online that would be greatly appreciated The petco is in the same area as me and uses the same water, they said the water is fine for guppies, neons, and corys.

 

[Byron]

I found what we need in the water report.  Once I knew it was NYC, I had a fairly good idea anyway, as I have discussed this water with other members previously.  Anyway, you have very soft water.  If you open the report link and scroll down to Table 1, it has "Hardness (mg/liter CaCO3)" aqnd this is the GH.  The measurement unit is mg/l, which is the same as ppm (parts per million) that is more common in the hobby.  There is also degrees GH that can be converted with the number 17.9...multiply ppm by 17.9 to get the equivalent dGH, or divide dGH by 17.9 to get the ppm.  So your average is 20 mg/l or 20 ppm, or 1.1 dGH, which as I say is very soft.  I have even softer water here at 7-8 ppm, less than 1 dGH.
 
The KH is the Alkalinity in this same chart, shown as 15.7 which is again less than 1 dKH [same conversion applies for KH as GH], so this means your pH will tend to naturally lower as the aquarium water builds up organics which produce carbonic acid and CO2, and thus the pH lowers.
 
What this means is that you are very well suited to soft water fish.  This covers the majority of South American and SE Asian fish, which are by far the most common.  Avoid all livebearers (guppy, molly, platy, swordtail) as these must have calcium in the water and will not last very long without.  Also rift lake cichlids need very hard water (by comparison) but you haven't space for any of them anyway.  
 
So, your neon tetra and corys will thrive.  Forget the guppies.  While this is a livebearer, it is true that with all the years of inbreeding it has become rather adapted to almost any water, but I still hold that it does better with some mineral.  Plus, this inbreeding has severely weakened this fish, and they are now fraught with issues unless one has a very reliable (independent) breeding source.
 
The neons at 10 will be better than fewer.  This applies to all shoaling fish.  But, you could find another shoaling fish, and have say 7-8 neons and 7-8 of another similar small tetra, or rasbora (the Hengeli mentioned earlier would be lovely).  Plus the six corys.  You should have some good fish stores in NYC, so you might want to have a look at what they offer.  Just stay with soft water fish.  Check back here before buying any, as you want to do research.  There are not many characins I or others don't know about.

 
Byron.

 

[driger8642]

I found what we need in the water report.  Once I knew it was NYC, I had a fairly good idea anyway, as I have discussed this water with other members previously.  Anyway, you have very soft water.  If you open the report link and scroll down to Table 1, it has "Hardness (mg/liter CaCO3)" aqnd this is the GH.  The measurement unit is mg/l, which is the same as ppm (parts per million) that is more common in the hobby.  There is also degrees GH that can be converted with the number 17.9...multiply ppm by 17.9 to get the equivalent dGH, or divide dGH by 17.9 to get the ppm.  So your average is 20 mg/l or 20 ppm, or 1.1 dGH, which as I say is very soft.  I have even softer water here at 7-8 ppm, less than 1 dGH.
 
The KH is the Alkalinity in this same chart, shown as 15.7 which is again less than 1 dKH [same conversion applies for KH as GH], so this means your pH will tend to naturally lower as the aquarium water builds up organics which produce carbonic acid and CO2, and thus the pH lowers.
 
What this means is that you are very well suited to soft water fish.  This covers the majority of South American and SE Asian fish, which are by far the most common.  Avoid all livebearers (guppy, molly, platy, swordtail) as these must have calcium in the water and will not last very long without.  Also rift lake cichlids need very hard water (by comparison) but you haven't space for any of them anyway.  
 
So, your neon tetra and corys will thrive.  Forget the guppies.  While this is a livebearer, it is true that with all the years of inbreeding it has become rather adapted to almost any water, but I still hold that it does better with some mineral.  Plus, this inbreeding has severely weakened this fish, and they are now fraught with issues unless one has a very reliable (independent) breeding source.
 
The neons at 10 will be better than fewer.  This applies to all shoaling fish.  But, you could find another shoaling fish, and have say 7-8 neons and 7-8 of another similar small tetra, or rasbora (the Hengeli mentioned earlier would be lovely).  Plus the six corys.  You should have some good fish stores in NYC, so you might want to have a look at what they offer.  Just stay with soft water fish.  Check back here before buying any, as you want to do research.  There are not many characins I or others don't know about.

 
Byron.

Awesome, thanks alot for that hardness levels , great for the cory and tetra, but sucks for the guppy; really liked that one xD. Any other fish recommended thats like the Guppy (fancy, like a center piece for the tank, doesnt get too big and dont need more than 2 in a tank) and will fit fine with the tank and tank mates? If not, I guess I'll have to go with the Hengeli. Would there be some way to make the water good enough for the guppy?

 

[StevenF]

my fish suggestion would be about 8 neon tetra and 8 Celestial pearl Danios.  I would start out with the neons first and then if the perameters stay fine and the Danios.    

 

[Byron]

Any other fish recommended thats like the Guppy (fancy, like a center piece for the tank, doesnt get too big and dont need more than 2 in a tank) and will fit fine with the tank and tank mates? If not, I guess I'll have to go with the Hengeli. Would there be some way to make the water good enough for the guppy?
 

 
"Centrepiece" fish are often wanted, but generally these do not work in small tanks.  However, here we come back to the Honey Gourami; one of these with the neons and corys would be fine.
 
Here i will digress for a moment, because this is an aquarium for your son and you want it interesting.  "Centrepiece" fish are usually more sedate than some of the shoaling species.  And the Honey Gourami, while beautiful, is not going to "do" much, if you follow.  Actually, the neons won't either.  So I can understand the desire for something a bit more active, like the guppies.  However, this brings us back to earlier comments about factors that affect what fish a given tank can hold.  The activity level of fish is very important.  I have seven tanks in my fish room, and while all contain relatively small species in groups, there are fish in the 90g that I would never put in with the fish in the 70g or 115g, simply because they swim too much.  Less active fish can be stressed out by activer swimmers around them, permanently.  The other thing is that the more active a fish is, the more space it automatically needs to be "normal."  As a rough example, my 29g has 64 fish in it, and there is no problem because they are all so similar in every respect...water parameters, activity level, environmental needs, water current.  But in this same aquarium, a group of 40 Zebra danio, which are roughly the same body mass as the present 64 fish, would never work simply because of the space.
 
To your last question, yes, you can harden water, but once you start adjusting water parameters you get into a very different situation.  And, if you did harden the water, you would be negatively impacting the neons especially.  I can assure you that all else being equal, neons will absolutely be healthier and live longer (= normal) lifespans in your water than they will in moderately hard water.  Parameters make a difference, and we cannot change the physiology of a fish to suit our whims.  This is why I have the two citations in my signature block.
 
It is always safest to select fish that will thrive in the water we have at hand, rather than having to provide something else.  I have done it, but then the fish in that aquarium need to have similar needs, or someone is still going to lose out.
 
Byron.