I have daphnia and baby mozzy larvae in my tank for my babies, but I do have some very tiny little white things in my daphnia tub outside. I was actually wondering if my babies would eat them but they seem to be ignoring the brineshrimp for the larger stuff, daphnia/live bloodworm/mozzy larvae/baby earthworms chopped, so may just ignore them.
It has been warm here, I thought summer would never arrive! I change two of my sisters tanks every 2-3 days, just 20-30%, but they're unfiltered and need to be.
Have you done a big water change recently; if you did you might have kicked your tank into a minicycle (or re-cycle if ya know what i mean!)
Maybe to check if it is doing a minicycle get the water tested to see if the ammonia or nitrite levels are rising above 0.
