How can I know how many fish is a reasonable amount to put in a tank.

I have a 30 gall freshwater tank.

Depends on what type of fish you plan to have, and how bit they will grow as they age.

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"Being ignorant is not so much a Shame, as being unwilling to learn".-- Benjamin Franklin

Summer is correct,the types of fish you have will determine how many you can house.

For one thing,that many do not take into account is the aggression level of the fish.Some fish are schoolers,non aggressive and do best in groups.Some fish are pretty aggressive and will be happy being the solitary fish occypying a section(top,middle,bottom.)Some fish get quite big contrary to how they look in the store(commom plecos,goldfish,oscars,assorted cichlids,flowerhorns)Some stay pretty small,and are mellow types.

I suggest you find a fish at the store you like,go home and research the adult size,temperament,and care level.

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http://bountifulbettas.blogspot.com/

"Come to the dark side....we have cookies...and filters/heaters/and water changes!"

A general reference for people new to this is 1 inch per gallon of water. Your tank is a 30g, but if I had to guess I'd say you have about 27g actually in the tank. So 27 total inches of "Adult" fish. So when you buy them and they are 1/2" long at that time, you should already figure in the extra inch that they can grow to if their adult size is 1.5 inches.

However, the rule doesn't work for every fish. Things like goldfish...because of the way they are your tank could possibly have two goldfish in it. Angels....obviously a lot of vertical consideration for an Angel and they just need room to move. Bottom line, you should research a fish before you buy it. That way you won't mix in-compatible species or coldwater vs tropicals, etc..

I had the same question a while and someone gave me a link to a calculator. I thought it was helpfull so I'll give it to you. Its not exact but gives you a good place to start from.

AqAdvisor - Intelligent Freshwater Tropical Fish Aquarium Stocking Calculator and Aquarium Tank/Filter Advisor

Good morning the...

I base the number of fish on how large the fish gets and how often I want to change out the tank water.

Here's an example: I have a 30 G, well planted tank and like Fancy Guppies. The adult fish are less than a couple of inches long. I'm also a water change fanatic. That means every week I remove at least half the water in the tank.

If you do large and frequent water changes, you guarantee the fish and plants have a stable, clean environment. To me, than means I can have a lot more fish than the person who doesn't change the water as often.

I have at least 60 individuals in my 30 G and my fish are very healthy. And, by flushing a lot of clean, treated water through the tank, I never have to test the water, because I know it's always clean.

This works for me.

B

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Low Tech Water Building Keeper

If you are new to fishkeeping, don't try to go way beyond the fairly well established bounds of keeping a healthy tank. Keeping more usually requires more experience. Wall-to-wall fish in a fairly small tank is not for someone new to fishkeeping. Doing that is why you are having the problems you are having.

jrman... Is totally correct. Not all new waterkeepers understand or want to devote the time to sound tank management. I was fortunate. I was taught the importance of large and weekly water changes from the start. This step alone, saved a lot of fish their lives as I was trying to learn the basics.

If you're unwilling or for what ever reason you're unable to change a minimum of half the tank water weekly, then you never want to have more than a few fish in any tank. The waste that will build up in the tank due to marginal tank management will kill your fish and sour you on the whole waterkeeping hobby.

Thanks jr for your advice!

B

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Low Tech Water Building Keeper

Thanks for this, neat little calculator

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Chris
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