Hi, I'm very new to keeping fish. I've just added 2 new platy to my 37ltr tank which had 2 platy in. I've just noticed a white spot on the tail of a new one but I can't tell if it's ich or just it's pattern? Could I get some advice please?
That doesn't look like whitespot to me (yet). Whitespot tends to look like sugar or salt sprinkles over a fish. I would keep an eye on the situation over the next while, so that you can learn whether that's just normal for him or whether it evolves into something different or if anything else untoward develops.
I always think it's helpful to have some medication in the fishkeeping cupboard, just in case an illness ever develops and you need to medicate quickly. I've always kept eSHa Exit (for whitespot) and eSHa 2000 (for bacterial infection) in the cupboard for that very reason.