I never really had to check my water parameters for any of my favorite fish and i dont really know how to do that but, i know how to keep my water good as when i was introduced to the hobby i had my share of trials and errors, so what i usually do is put some aquarium salt in it and then add ani-chlorine, anti fungus if needed, triple black water and vitamins. And then the water is acceptable for any fish that i had or have they did not have any issues with the water quality. Any way i am will to learn about parameters and how to check it.Definitely a gator gar. Like BIG-G since it's been some months...use some feeders. Been too long. I'm sure adults can go without a while but not young fish.
Would advise guppies instead. Rosy red and goldfish have low in nutrients and thiaminase. But quarantine all feeders with salt and prazi/MB. Safest way.
How's ur water parameters by the way?