platy, livebarers

Question
tank is 20 Gal,and is 5 weeks old.2 red platys,1 is larger,and i think there m and f.1 algee eater(2 1/2 in long) and 2 albino cat fish,2 silver and black stripe Sharks,(very friendly but stupid).reg ph and reg filter,w/ ph filter added,heater set on 78 deg ,all fish are fine,but the larger platy,(i think is male cause anal fin is folded closed)has been chasing the smaller one latly.I think its a female cause her anal fin is displayed and open..she looks fat and has been for weeks now ,but has been acting different ,hiding behind things ,like the heater or in the boat ect...my ? of course,is whats going on with my platy is she sick or prego or what?

Answer
Hi Myst;

Platy males want to breed ALL the time! It is best to have 3 females per male to give the females a chance to rest. If they are pregnant, they will try to hide from the male. If he harrasses her too much she could die. Get 2 or three more females and they should be fine.

More hiding places like plants is very helpful too. He can't see her all the time so she can rest.

Followups welcome

At Your Service;
Chris Robbins