I lost one of my little guys last night. He had gotten himself stuck in a hole in the bottom of a pot. Make sure your holes are big enough for them to get through if you have them. I thought mine was, but he got to fat. He will be missed. Hope this never happens to you guys.
Becareful with either of these guys, I lost one yesterday. He got stuck in the hole in my clown loaches pot. I wasn't home at the time, poor guy. Just a word of warning, don't have anything they can get into and not out of. He will be missed.
I'd get a snail or something to start cycling your tank. Thats what i did with my 10 gallon, although I do have gravel on the bottom and live plants in it. Works very well for a fry tank. Have a bunch of 1" long mollies now. Didn't loose 1 since birth.
They are great fish, sleep all the time though. I only have 1 at the moment, he sleeps in a pot nearly 75% of the day along with my 2 dojos. Great fish. Loaches are the coolest.
Koi can live to be around 100 as far as I have read.. I'd imagine you could send your great grandkids back to the lake and if nothing catosrophic has happend those fish might still be there doing the same thing.
He might try to breed with the platies, I doubt highly that they can cross breed. But i'm not entirely sure. If you want babies get a female molly and some will pop out in 30-60 days.