I've never tested the water. Nor checked the cycle. I had always just changed 1/2 the water every week. And totally changed it out every so often. I never thought that it would hurt them if they had nice clean water weekly.
I'm debating on what kind of fish I'd like to get again. All the fish I've had, were not picked by me. My grandson got fish for a present the first time for a birthday gift from his deadbeat dad. So, of course, I ended up taking care of em. They were at his moms house, but she was not taking care of them.
This time I'll pick.
Maybe a bunch of guppies.
Rip, I love guppies, and I won't bag on your fishkeeping skills. It can be a very tricky business.
I change 50% every 3 days on some tanks, because I have too many fish. My systems can handle the ammonia but eventually build up with nitrates.
Depending on the biology a 90% change may be needed on occasion, but I do it slowly.
The best thing is really a drip system IMO. The water changes continually, from water in a conditioning tank.
This really allows you to control the chemistry.
Some tanks hardly ever need changing.
Some guy on YouTube named Dr. Kevin Novak has planted tanks with special filtration he doesn't change for 6 months.
If your water is rather hard or rather soft, it can pay to pick fish that need that type of water.
I have soft water, but some real hard water fish, and I put a lot of coral sand and crushed oyster shell in the tank.
It buffers the water, but slowly, so if I do a big change the pH and general hardness can swing suddenly.
I have to be careful about doing big changes. I will usually take an hour to do a change I could do in 10 mins with a hose.
If your fish are already infected, a big swing in pH can kill them.
If you bleach your tank and use new filters, it will take about a month to age it from scratch, and get the ammonia cycle going strong.
You can force this, by using cycled gravel, etc, which is already covered in healthy bacteria.
But if it's not 100% healthy you can be forcing the wrong stuff.
And if you add fish too quickly, the filter bacteria (most of the beneficial bacteria in a healthy tank live on the filters) can't bloom fast enough to keep up with increased waste.
This means increased water changes for you until the ammonia levels stabilize to zero, as the filters finally "cycle in".
What they call cycling or ammonia cycling, we used to call aging. We knew that a new tank would need to age, so we'd put one little fish in, and let it start the biology going.
After some aging, you can slowly add more fish, but never so much as to strain the bacteria. When the bacterial colony "chokes" from too much feces, ammonia isn't broken down and the fish get burned gills and weak kidneys. This "ammonia cycle" chemistry wasn't well known back when I started. We knew what to do but didn't know exactly why.
The thing is that fish can often be quite ill, yet recover with a water change and live for years.
But they will be forever weakened, and highly susceptible to some things a normal fish could survive without issue.
They will usually not grow quickly or breed well, once they have suffered from ammonia.
It's a big deal that the ammonia levels are never allowed to rise above the minimum.