A couple of months ago I setup a 60L tank with some Pam's potting mix, and covered the mix with fine pumice ( most of which sank ), and then planted a couple of plants that weren't doing so well elsewhere. As I recall nitrates were pretty high and I left things alone. My neighbour gave me a bucket of plants from his tropical tanks 2 weeks ago. Rather than try and plant them into fish tanks, I thought I'd use this 60L tank as the quarantine tank. Included were vals with leaves over 1 m long, some crypts, java ferns, oxygen weed (from his bath tub ) and a few other things. I washed them in aged water to try and get rid of most of the algae and planted the rooted plants. I moved the tank to a window, but left it unheated. The crypts melted, but looks like some new leaves are appearing.
A couple of day ago I saw 4 fry swimming there. Odd really as he thinks he only has live bearers, and hard to imagine that fry survived washing, and a cold tank! His tank did have guppy and some swordtail fry present.
To give them a chance I put a heater in set at 20 deg. The tank heats up to about 25 deg in the sun, and most all of the plants are bubbling away.
The fry are 3-5 mm long head to tail, and neighbour suggested I just feed them with powdered tropical flake. I presume that they have been living on algae, or microscopic aquatic life. After I put the flake in yesterday, I can only now see 3 fry, so perhaps I'll just let them eat algae and protozoa. There are also a few tiny worms, white tiny things that swim in a brownian fashion, and lots of snails, and algae.
Ammonia is < 0.02ppm, and nitrates have dropped from very red several months ago to 0-5 ppm when tested today. I did a 90% water change at the time I added the new plants so that might explain why the nitrates have dropped so much. Pam's potting mix doesn't explicitly added fertilizers though they say there might be some present.
So, should I remove these fry and put them into a net and raise them in a tropical tank? Or just let them get on with it?