new tank, first fish

Question
QUESTION: hi Nathan, have been regularly reading your replies to various questions raised here. must say, i quite trust you now to ask mine. i have a 25 gallon tank which i will cycle soon. how long do i need to wait before i inhabit it with fish? what kind of fish and how many should go in first? can i place gold fish in the tank with other freshwater fish? i want my fish to be healthy and long-living, how many fish will be enough for a 2ft wide, 1ft deep and 1 1/4 ft tall tank? thanks in advance.

ANSWER: Hi Hina,

You've made a great decision to keep fish... Did you know:

Watching an aquarium is scientifically proven to reduce stress?

First of all, make sure you have the following pieces of support equipment:

-Tank (Well, obviously!)
-Filter
-Lighting
-Gravel or Sand
-Artificial or live plants (Goldfish plastic, others live)
-Heater (tropicals only)
-Thermometer
-Gravel vacuum/siphon

You can keep Goldfish OR Tropical fish. Goldfish cannot co-exist with tropical fish. Goldfish need temperatures of under 70F, while tropical fish need temperatures of 75F or greater. Keeping Goldfish with tropical fish will kill one of the two.

If you're planning on keeping ONLY Goldfish, you do not need a heater. If you're keeping tropicals, you need a heater.

Set up everything, and let it run for 24 hours. (Heater, filter, etc.)

Then, you can add 2-3 fish.

These fish will be the fish that go through the cycling process. The cycling process is where you establish beneficial bacteria in your tank. You may be thinking, "Why do I need bacteria?" Well, fish constantly produce waste, and the decomposing waste turns into ammonia. Soon, natural bacteria will develop in your tank and a chain of different bacteria (Nitrosomonas and Nitrobacter) will populate your tank, changing toxic ammonia into nitrite, and then to nitrate. I know this may be confusing, but the point is, ammonia and nitrite (not nitrate) are poisonous, and so by keeping those few first fish in the tank (and only those fish) will finish the cycling process, which means you will have a continouos supply of de-toxifying bacteria. The cycle will be finished after one or two months, after which you can add more fish.

The reason why you don't add all your fish at once is because the ammonia from the fish waste will kill all the fish. This is why, if you've ever experienced, people will add some goldfish into a bowl, and they die the next day.

-Set up everything
-Let run for 24 hours
-Add 2-4 fish (Goldfish OR Tropical)
-Perform 15-25% water changes every three days
(this will reduce the concentration of toxins while your bacteria develop)
-After 3-5 weeks, you can start populating your aquarium with other fish (add 2-3 once or twice a week, don't add them all in).

After this first month, you can switch to a regular routine of a 10-20% water change once a week.

Please see this extremely helpful guide from Hagen Products. This is actually one of the first guides I read (well, an older copy of it), when starting one of my first tanks.

http://www.hagen.com/pdf/aquatic/bag.pdf

See this for the cycling process:

http://www.worldcichlids.com/faqs/cycling.html

Good Luck, and Happy Fishkeeping!

---------- FOLLOW-UP ----------

QUESTION: thanks nate for the guidance, however i am still unsure of who should be my first fish for cycling the tank with them. i know they have to be hardy and i will want to keep them for later too. please suggest an article or give me atleast five options. my tank will be a peaceful one, so aggressive fish will not help. thanks again. keep up the good work!

Answer
Hi Hina,

Your first fish should be hardy ones, such as

-Zebra Danios
-Guppies
-Corydoras Catfish
-Betta (One male only, or multiple females, but not both)
-Harlequin Rasbora
-Swordtail
-Platy Fish

These fish are all colorful and lively. (and hardy)

See this for more info:
http://www.worldcichlids.com/faqs/cycling.html

Good Luck, and Happy Fishkeeping!