Tropical Fish Is it overcrowded and do fish grow to the size of your tank?

Question

I'm relatively new to tropical fish keeping although my family have fish tanks. I keep freshwater fish - a lush mixture of colourful very small guppies and a male simese fighting fish, some tetras (neon) and much more, but all of the small, guppy and molly, tetras. I have perhaps all together 19-22 small fishes. The biggest is the darf Gourami, which is only 7cm long. I have several bottom fish feeders. 2 live plants, a small rock and one slate - all look very well. 3 way high filter with air pump and you name it i have it.

My tank is a hexogan 6 side tank, 5.7 US gallon. I work out the sq area to be just below 1500cm sq I believe.
I dont think of getting more fish - unless i removed some and taking them back to the shop where they're happy to take fish.

My fish are incredibly healthy, happy and look very well!
the water is clean - and everything is happy and compatible.
But, i am worried of oversizing , can anyone tell me if a small tank is too small? Thank you :)

Answer 1

Common Glass Aquarium Sizes

5.5 Gallon 16x8x10 (128 sq. in.)
10 Leader 20x10x12 (200 sq. in.)
10 Hexagon 14x12x18 (127 sq. in)
15 Gallon 24x12x12 (288 sq. in.)
20 High 24x12x16 (288 sq. in.)
20 Long 30x12x12 (360 sq. in.)
25 Gallon 24x12x20 (288 sq. in.)
29 Gallon 30x12x18 (360 sq. in.)
30 Gallon 36x12x16 (432 sq. in.)
30 Breeder 36x18x12 (648 sq. in.)
33 Long 48x13x12 (624 sq. in.)
37 Gallon 30x12x22 (360 sq. in.)
38 Gallon 36x12x20 (432 sq. in.)
40 Long 48x13x16 (624 sq. in.)
40 Breeder 36x18x16 (648 sq. in.)
45 Gallon 36x12x24 (360 sq. in.)
50 Gallon 36x18x18 (648 sq. in.)
55 Gallon 48x13x20 (624 sq. in.)
65 Gallon 36x18x24 (648 sq. in.)
Petite body fish
1” per gallon or 1” per 12 sq. in. of surface
For example 20 long has 360 sq. in. surface area
360/12=30
Can a 20 long support 30” of fish? Probably not.
A 20 high has only 288 sq. in. surface area
288/12=24
Can a 20 long support 20” of fish? Probably not.
A 25 is also 288 sq. in. surface area
288/12=24
Can a 25 support 24” of fish. Probably.
I like to average the two for a more accurate capacity.
For the 20 long, 30 by surface area, 20 by volume averages to 25”
Can a 20 long support 25” of fish? Probably.
For the 20 high, 24 by surface area, 20 by volume averages to 22”
Can a 20 high support 22” of fish? Probably.
Why does the 20 long support 3” more fish that the 20 high?
A larger surface area allows a greater oxygen exchange, which is as important as volume of water.
Large bodied fish, such as gold fish you need to double or even triple these numbers, i.e. 3 gallons per inch and 36 sq. in. of surface per 1” of fish.
This is not the only consideration for fish tanks. Types of fish will appreciate one type of tank over another. For example, fast swimmers like Zebra Danios, Pearl Danios and Blue Danios will do best in a tank that is at least 30” long. They would be better kept in a 20 long rather than a 25. Giant Danios would do best in a tank at least 48” long. They would be better kept in a 55 rather than a 65.
On the other hand, slow, tall bodied fish like Angel Fish and Discus will do best in a deep tank. They would be better kept in a 65 rather than a 55. They, like other cichlids also need a bit more than the 1” per gallon and/or 12 sq. in. surface.

Answer 2

I'm sorry but the old wives tale of fish growing to the size of the tank is totally WRONG! If I had a dollar for every time I heard this one I would be rich. I have been keeping fish for over 20 years now & all fish grow to a certain size according to species. They may vary somewhat, some may be smaller than others just like dogs & cats, there can be few runts or a few giants, but basically they all grow to pretty much a standard size for the species. So do your homework before buying new fish & make sure they are within your size limits. Your tank is too small for the amount of fish in it & I wouldn't add any more, but you must be doing something right. Otherwise you would be experiencing alot of problems. So keep doing what you are doing. As long as it works don't fix it! If you start having problems in the future consider a larger tank. But if I were you I would fix the problem before it starts. Until then I would recommend 20% daily water changes & keep a close eye on the water parameters. Test , test, test .Hope this helps! Good Luck!

Answer 3

Your tank is seriously over crowded! and under filtrated. 5.7 gallons isn't nearly enough for 22 even small fish. Mollies alone over load the tank. You are forgetting these fish will grow. your tank is even too small for a 10 gallon. Healthy or not they will not remain that way. What are your water test reading? you should with that many fish be testing every day.

I would get rid of the dwarf gourami and one or two bottom feeders. One is fine. More than one molly is too many, how many tetras? more than one too many. Get a 10 gallon and keep the tetras, and guppies and one bottom feeder.

Seriously too small Yikes. These fish have no where to go, let alone grow healthy. Even in a 10 it will be crowded. But manageable. Just because the water is clean does not make for a healthy environment. There are many things going on in the tank you cannot see. Even with the slate, rock and plant, your water displacement is down around 5.1 US gallons. I don't want to sound harsh but your fish are small and you have gotten lucky. It won't last for long. They need a bigger tank.

Fish never grow to the size of the tank or we would all have bonzi fish. That is a myth. Or I would have a great white in my 175 salt.

Answer 4

Your tank is way to small for the amount of fish you have in it. They will have trouble growing ,Ammonia will build up quickly and you will also end up with a large die off of most of your fish.For the amount of fish you have the smallest you can do is a 29/30 gallon tank no less.

Answer 5

I believe for that many fish, your 5 gal tank is too small. I was always told that you can have 2 fish per gallon of water. With 25 fish, you should have a 50 gallon tank. I had a tank once with the same breeds of fish you had. The guppies and mollies had babies so fast it wasn't funny. My Gourami was extremely agressive, and ate almost everything in the tank. I eventually got rid of him because he did not play well with others. But he ate real well because of all the guppy and molly babies he had to snack on!

Answer 6

Your tank is severly over crowded.
In a 5 gallon tank, you should have 5 guppies. That's it.
OR
1 gorami
OR
2 Mollies
OR
5 neon fish
OR
2 tetras.
Not all of them together.

They look fine now, but in about 2 weeks or so they will start dying off.
Get a 30 gallon for all those fish!
And talk to the pet store employees. They can help you.

Answer 7

The correct equation for fish and tank size is 1 inch of fish per gallon, and you have to look at their adult sizes, not the size they are now. You really can't deem your water "clean" until you purchase a master test kit to test ammonia, nitrite, and nitrate. Just because the water looks clean doesn't mean its clean. I talk to alot of people and friends who wonder why their fish is sick and claim their water is clean, only to ask and then find out that they never tested their water. Theres active chemicals in your tank that you cant see unless its tested. If you do have a master test kit, ammonia should read 0 ppm, nitrite should read 0 ppm, and nitrate should read between 20-40ppm preferrably.

Answer 8

You should have no less than one gallon of water per square inch of fish. I takes same creative thinking to convert fish into square inches, but a close approximation is sufficient.
Also, some fish will continue to grow if placed in larger and larger tanks, like goldfish, but not all will. Ask the people you're buying the fish from, and if they don't know, find a different supplier because that would indicate a sub-par knowledge of their wares.

Answer 9

that tank is WAY too small. For yours I'd suggest a 20 to 30 gallon tank with your fish you have.

Answer 10

I would get a bigger tank and get rid of some of the fish,I think you are really over crowded.I would get a 20 gallon tank if you can afford one .I find the bigger tanks are easier to take care of especially for a beginner.It's a myth that fish will grow to the size of your tank.