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I have a 20 gallon tank. In this tank I have.

2 Black Skirt Tetras
2 Fancy Finned Black Skirt Tetras
2 Lemon Tetras
2 Serpae Tatras
2 Fancy Finned Red Tetras
1 Dalmation Molly
1 Black Lyretail Molly
1 Silver Lyretail Molly
1 Calico Carp
1 White Fantail Koi
2 Dwarf Flame Gourmis
2 Dwarf Honey Gourmis

and (Drum roll please)

1 Female Fiddler Crab

Now I know this sounds like a lot of fish but all but 2 of then are small (less than an inch)

The two large ones are the carp and the Koi and both are 3" plus bodied.

The question is I have read and heard a lot of people say that Tetras should be kept in large schools, but my Tetras all school together as one school. Is this normal or are they compensating for lack of they're own kind?




PS oh yeah! I forgot the two Black Mystery snails and the approximately 35 small unidentified snails that came hidden inside a giant Goldmantle a long time ago. (at one time there were several thousand of these little buggers but the carp and koi find them a tasty in between meal snack occasioanally.)

When failure has occured after the begining of a series of attempts, make further attempts.

To answer your question first, is yes tetra's normally like to school together and it is best if they are kept in groups of 6 or more because of this. However, as you mentioned tetra's of similar species will school together though when there is a limited number of their own kind around.

Now and as you stated you have a lot of fish in that small of tank and you are very heavily overstocked. The koi alone needs to be in a large pond in my opinion of no less that 1,000 gallons.

You really need to consider trading off some of your fish because you are courting a disaster. Which ones you should keep are really up to you, but you need to do a little research and limit what you have to your tank's capacity. I won't say anymore about it as I'm sure there are going to be many others that will give you similar advice.

Jim

---

Water, taken in moderation, cannot hurt anybody. -- Mark Twain

You are! Get the Koi and the carp out of there, and cut the number of your remaining fish by 40% -- FAST -- or you'll have a sudden tank wipeout in which you'll lose more fish than that.

And don't forget that when you overcrowd fish and force them to breathe water contaminated with their own ammonia, you are literally forcing the poor little devils to breathe poison gas -- as well as tempting them to eat partially-decayed food, which will give them food poisoning and cause them to literally start rotting away from the inside.

Finally, Mollies really do not do at all well in regular community tanks. They absolutely require a small amount of salt in their water (which they live in in the wild), or their immune systems collapse and they start suffering from various godawful skin diseases. (You could keep them very nicely in a separate tank with, for instance, Celebes Rainbow Fish, which have the same problem.)

Ditto what OldTimer said!

Also, IMO a 20g is only big enough for 1 school of fish (6-8) and a centerpiece fish or two. I think that you could get away with 2 schools of 6, the mollies, and 1 pair of dwarf gouramis (go for the honeys ). Thats it. I'd do something with koi, carp, crab and other pair of DGs. That would still be pushing the limit IMO. Koi belong in a pond and I believe carp get pretty big as well.

Now I know this sounds like a lot of fish but all but 2 of then are small (less than an inch)

When stocking a tank, you should keep in mind the adult size of a fish. They may be small now, but will grow. The Black skirts get pretty big, about 2.5-3 inches. They really belong in a tank bigger than 20g IMO. I'm guessing the Fancy Finned red tetras are Serpaes. They are pretty nippy, so I'd take them out. The Koi and carp IMO shouldn't be in an aquarium at all...unless its as big as a pond.
Also, tetras are schooling fish and would prefer to have atleast 4 of their own kind. But you'll have to lose 2 types IMO.

*Kristin*

I don't know about the carp because he is new to the tank but the Koi is now 7 years old and has not grown at all for the last 5 of them he may be some kind of dwarf spieces. (My girlfriend had him before she moved in. I will be upgrading to a larger tank in the near future. I have my eye on a 150 gallon set up with a very nice cherry wood stand.

I test for ammonia, and Nitrates every other day and yet to see a rise in them in over 2 months since the new fish were added (all the tetras except the black skirts) and all of the fish get along well. We never see any fights in the tank. I was rather surprised at the carp and koi as I figgured they would bully the tetras but they leave them alone.

I have totaled up the fish length in the tank and came out to 17" that pretty close to fits the 1 inch per gallon rule and gives a little bit of grow room for them before the big tank is a must.

We had one fish that was a fin nipper and he now resides over a friends house in a large aquarium.

The crab was a buy for my girlfriends son he really likes crabs and I talked him into a female because they dont have large claws. The crab has been an excellent addition because she keeps the bottom of the tank as clean as a new one.

It has been a long time since I have had an aquarium but even when I was a kid I used to keep odd combinations togather and do well. I had a 20 gallon with 2 huge oscars (6" plus length) and a bunch of neons (10) and 2 Dojo eels. The oscars ate feeder goldfish but left the other fish alone. I could not add any other fish because any new fish was a feeder to the oscars. I hade to get rid of the oscarswhen they finally out grew even the upgraded 55 gallon I got for them. (they were both over 15" long by then.) When I got rid of them I lost interest in fish and sold all of my tanks.

Now new girlfriend comes into my life and I have fish again...



When failure has occured after the begining of a series of attempts, make further attempts.

I'm guessing the Fancy Finned red tetras are Serpaes.

Actually they look just like Red Tetras except they have very long and flowing fins.

http://www.fishprofiles.com/files/profiles/587.htm

When failure has occured after the begining of a series of attempts, make further attempts.

2 6inch oscars in a 20 gallon!!!! you were torturing them. Anyway if you get a 150 you can put wour fish in their and up your tetra schools to about 6 each


-Vincent

That is the plan.

When failure has occured after the begining of a series of attempts, make further attempts.

Be extremely skeptical about that "1 inch per gallon" rule -- never forget that any fish twice as long as another one, if they have the same body shape, has EIGHT times as much flesh and thus eight times as much metabolism. By the same "volume cube rule", an 8-inch-long fish will consume fully FIVE HUNDRED AND TWELVE times as much oxygen, and produce 512 times as much waste, as a 1-inch-long fish with the same body shape -- NOT just eight times as much.

Interesting thought...

Doesn't follow the basic rules of biology.

If that were true than an adult human would eat eight times as much food and drink eight times as much fluid as a five year old child...





When failure has occured after the begining of a series of attempts, make further attempts.

Nevertheless, not only does it make elementary mathematical sense, but I've heard the phenomenon described in many an aquarium book. Once again: you have got that tank VERY seriously overcrowded, and will eventually regret the fact. (Also, just how much DOES an adult human eat daily comapred to a 5-yar-old?)

I eat about three times what my girlfriends 8 year old does and I am 6 times his mass. But I am a large person at 300 lbs. The average adult at 200 lbs would eat about 3 times as mush as a 5 year old child.

Oxygen use is about the same, my search and rescue courses taught me the calculations for oxygen use and room volume. and the typical adult will count as three children under 7 and 2 under 14.

I ran an water oxygen content test today on the water in my tank and found that I have about 8 times the air pump I need, I have an air pump for a 100 gallon and an air pump for a 60 gallon running on my tank at the same time. Plus my Biowheel filter is for a 100 gallon tank.

Frequent water changers (25% twice a week) keep the Nitrates low and I test the water every other day. for any signs of trouble.

While I wont be adding any fish to the tank I will not be getting rid of any either.

by the way can you get a fish fixed?!?

When failure has occured after the begining of a series of attempts, make further attempts.

I shouldn't even touch this post. I call this abuse and you shouldn't have fish. The reason your koi hasn't grown isn't because it's a dwarf type but because it's stunted. I highly suggest you do a search on stunting.

While a fish several times wider and thicker in body may not produce that many times more waste it will produce much more waste. Some fish are also just naturally high waste producers and goldfish, koi, and other carp fall in that category. People have had trouble keeping nitrates low in 55g tanks with just a couple goldfish. In a 20g aside from not reaching their true adult size and lifespan due to stunting they will pollute the tank to the point the other fish will die. If you don't do something about this tank nature will and all those fish are going to be dead well before their natural lifespans.

* Points to this editorial piece ... *

It's a long piece, but you may find it well worth persevering with.


Panda Catfish fan and keeper/breeder since Christmas 2002

Very well written article.

When failure has occured after the begining of a series of attempts, make further attempts.

You say your nitrates doesn't get high...what is it?

Ok when you use the inch per gallon rule...you go by the adult size of the fish. Here is a break down, using the adult lengths from FPs profiles:

black skirts:~2.5in x4 is 10
lemons ~1.5in x2 is 3
serpaes 1.5in x2 is 3
red tetras 1.5in x2 is 3 (guess on size)
mollies 4in x3 is 12
dwarf gourami 3.5in x2 is 7
honey gourami 2.8in x2 is 5.6

That adds up to 43.6 inches...and thats not counting the koi and carp which should both get really big, but won't because they are/will be stunted. I wrote everything out for you so you would see how the inch per gallon rule should work. Its not a good rule to go by though.

You are seriously overstocked!

edited to be nice


*Kristin*

The aquarium is severely overstocked, but there's no point in trying to shame the guy. The best that can be done is to present the facts, not to insult him. Please be more courteous.

---

And when he gets to Heaven, to Saint Peter he will tell: "One more Marine reporting, Sir! I've served my time in Hell."

Those huge water changes (which you didn't tell us about earlier) might be what makes the difference. If you're willing to go to THAT much trouble, you might be able to break the standard rules. The danger is, however, that if you run into some kind of life emergency that keeps you from doing even one or two of these changes on schedule, your fish have an excellent chance of heading for that Great Sushi Bar in the Sky before you can get home and correct the situation.

My water test from this morning.

Nitrates between 5 and 10 ppm (change done when it reaches 20)
Nitrites 0
Ammonia 0
Total hardness 150
Total Alkalinity 0
Ph 7.2
Water Temp 78 degrees

Actual Fish sizes and ages

black skirts: 3/4in .75, 7 years.
black skirts: 1/2in .5, 3 months in tank.
black skirts: 1/2in .5, 3 months in tank.
black skirts: 1/2in .5, 3 months in tank.
lemons 1/2in x2 is 1, 2 months
serpaes 1/2in x2 is 1, 2 months
red tetras 1/3in x2 is .66, 2 months
mollies .75in x3 is 2.25, 1 month
dwarf gourami 1in x2 is 2, 3 months
honey gourami 1in x2 is 2, 3 months
Koi 3in 3, 7 years
Carp 3in 3, 1 month

Total 17.16 inches.

Future tank size is going to be either a 150 gallon or a two 50 gallons. These will be purchased within the next 3 months. Then 1 month to fishless cycle the tank(s) and then the fish get new homes.

When failure has occured after the begining of a series of attempts, make further attempts.

A quick note.

I just got off the phone with the Fish store that the koi came from.

He has a 2900 gallon pond in his store with this type of koi in it he breads them.

His original breading pair are still there (he won't sell them) and they are only 5 inches long and 27 years old.

He does not know thier species, he got them from Singapore 27 years ago. They came in a shipment of goldfish and he kept them. He is not even sure they are a true koi. They have the barbles and body shape of a koi but have fan tails and fins and don't seam to grow as large as normal koi.

I need to do some research and see if I can identify this fish.

When failure has occured after the begining of a series of attempts, make further attempts.