One of my molly fry has a white blob on it's head. It started as a discolouration and doesn't look like ick. the molly is in a 2.5 gallon tanks with 5 other tiny fish and a handful of shrimp. I have not tested the water but the tank is planted and has been inhabited for ~ 4 months. The tank was also just treated for camallanus worms. I did a partial (regular) water change on Monday. Today I gave the fry a saltwater bath. Here are the photos

It could be a fungus or bacteria infection. I notice that in your second photo there are some dirt particles and the filter in the background (assuming it is a filter) looks dirty. When last did you give the filters a clean?

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45g pentagonal
4 Swordtails, 2 dwarf Gouramis, 5 Mollies, 1 Rainbow Shark, 6 Molly fry 6 zebra danios

88 gal Malawi tank
4 Yellow labs, 1 Baenshi, 2 Borleyis, 3 Trewavas, 2 Livingstonis, 1 Venustus, 2 Green Terrors

I was thinking fungi too - so I'll start anti-fungal treatment today - I just didn't want to start medication and be wrong. I clean out the filters each time (especially that one because it is clear and looks disgusting )- but it's a fiddly little thing and I have to admit on monday it got a quick swish and wipe clean because I was running out of time.