Hello mock...
Here's the skinny on cycling a tank with fish. It's not the no-no you've heard. You just need to know the basics and the fish will be fine. Ideally, you use 3 to 4 hardy fish for every 10 gallons of water. Rasboras, Platys, Guppies, White Clouds, and Zebra Danios are all good choices. You drop in a lot of stem plants to help filter the water. Hornwort, Common water weed and Pennywort are all good. I like to add a bit of standard aquarium salt, about a teaspoon for every 5 gallons of water. Salt helps calm the fish and strengthens the immune system.
You get a reliable water testing kit and start testing the tank water every day for traces of ammonia and nitrite. These toxins will starting to build up in a couple of days after you put in the fish. The fish waste starts the cycle. When a test shows of trace of either of these toxins, you change out 25 percent of the tank water and replace it with pure, treated tap water. If you don't change some of the water, the toxins will build up and kill the fish. Resist the urge to change more water, you're growing the good bacteria that will begin using the toxins for food. You don't want to remove all their food. If you do, they can't grow and you don't want to be cycling the tank a year from now. The process only takes about a month.
Just test every day and remove the water when needed. When several daily tests show no traces of the above toxins, the tank is cycled. From this time on, you just need to change half the tank water about every week or two to maintain stable water conditions.
Pretty simple if you carefully monitor the water chemistry.
B
