You do not need live fish for what you want to do. There is an easier and cheaper and safer way.
Yoou can purchase more ammonium chloride thqt you would need to keep a dozen 10 gal tanks cycled for the next 6 years for about $20.
https://www.amazon.com/Fritz-PRO-Ammonium-Chloride-500gm/dp/B00OTH5TAQ
One level teaspoon of ammonium chloride is approximately 4.5 grams, 4.5 grams per 100 gallons of aquarium water will create an ammonia concentration of approximately 4 ppm.
Now Fritz uses the Nitrogen scale so their 4 ppm is 5.12 ppm on an API style kit. So you only need 1/2 the dose they suggest. Do the math and you will see 4.5 gm is enough to dose 10 x 10 gal. tanks to about 2.6 ppm twice. Maintaining a cycle does not require adding ammonia every day. Every other day or even every 3rd day will do the trick. But lets work with every other day.
Since all you have are 2 x 10 gals., that 4.5 gm., using the above info, means you can keep 2 x 10 gal. tanks cycled by dosing every other day to 2.6 ppm for 20 days. So it works like this:
4.5 gm creates 2.6 ppm in 100 gals twice. 100/10 = 10 x 2 doses = 20 doses good for 10 gals. so that would be 10 doses for both of your 2 tanks. Since you only need to add the ammonia every other day, that lasts you for 20 days.
There are 500 gm. in the jar of Ammonium Chloride, that is 111 x 4.5 gm. = 499.5 which means it can dose the 2 tanks for 20 days x 111 = 2,220 days. This is just over 6 years.
The above math is based on the idea that each of the two 10 gals tanks will be cyclced to handle of full fish load. it assumes no live plants but some sand on the bottom and some decor (preferably which is bleachable if needed). A Q tank may become and H tank in some cases.
In my opinion, having a Q tank which starts by having other fish in it defeats the point of Q. Those resident fish may carry something they can fight off but which the new fish added cannot- oops. Or the new fish may have something the fish used to keep the tank cycled can catch- oops. Plus, my guess is that the cost of feeding a couple of BN for 6 years will cost more than $20? Plus with fish in the tank a simple weekly water change is not enough. The plecs ppop a lot and may not eat all they are fed, so you will need to vac somewhat regularly as well as to change water. Dosing ammonium chloride only requires water changes, no vacs and almost no filter media cleaning.
