There may be fin rot happening - can’t really tell from the photo ... BUT there are definite signs of external parasites
Depending on the BioOrb (60 litre?), fish load (platies don’t qualify in the typical “small slender fish” assumption made for fish/bio load recommendations) - the fish may do better if transferred to the new 60x 45 (x45? tall) aquarium
BUT if the new tank is nicely aquascaped, it’s not an ideal situation for treatment - bare tanks offer much better control of conditions, water volumes, medication “durability” and expected (chemical) activity, fish waste/food consumption etc
Plants can also respond adversely to medications (depending upon ingredients and duration of treatment)
At present,
- 25-50% water changes done every 12-24 hours (I’m wondering if there are water quality issues, eg, ammonia present)
- ich remedy such as eSHa Exit
- salt treatment for external parasites as most live bearers tolerate salt very well (eSHa Exit is likely a more efficient treatment, but you likely have suitable salt at hand)
Note if you guess correctly, you often see noticeable improvement within a couple hours, depending how ill fish may be ... also if the main infection is the external parasites or it the primary infection is internal (bacterial etc)
Live bearers also seem more likely to have mild “velvet” infections that respond to salt treatment
(Oödinium pilularis/Oödinium limneticum is not easy to eradicate except when the infection is mild)