Need advice☺️

[Jodiejo]

Hi guys... My 13yr old son bought a 60LT tropical aquarium in august with his bday money, we did a few weeks cycle before adding fish... Anyway everything has been perfect up until tuesday, but now one of his Dalmatian Molly's has been acting strange, tonight I've noticed he's been swimming with his head pointing down as tho as he's diving & then he'll flip over & swim upside down, can someone please give me advice on what the problem could be/or what I should do to help this fish... Thanks in advance

 

[aquandrew]

how did you cycle the tank? what are the ammonia, nitrite and nitrate levels? 60l is going to be too small for mollies, your going to want at least twice that