I'm new to fish forum, and I haven't kept fish in years, so I'm at a lost for how to handle my current situation. I have a 10g tank with two black mollies (male and female), a male high fin redtail black platy, and a female red platy.
I've had them for five or six days now, and over the past couple of days I've noticed a severe change in disposition of my red platy, Marvin. She was just as active as the other three fish for the first few days, exploring and eating with the others and playing a sort of friendly tag with my redtail, Merlin. A couple of days ago she started sitting on the bottom of the tank behind a plant, and would eat very little. Now she has taken to hiding in their skull cave all day long and won't come out to eat. I was able to get her to come out and eat last night and this morning, but only after all the others had eaten. Even then she only ate a little, and spat most of it back out, promptly returning to her cave. She is breathing faster than Merlin, but I've also noticed the female molly breathes faster than the male, so that may not be relevant. Marvin does not look ill, and does not show any sign of being bullied. She does not look pregnant, either. What do you think could be wrong? How should I handle it?
10g tank (conditioned freshwater)
77-80 degrees F (still trying to figure out the heater)
I do not have a water testing kit yet. What kind do you suggest?
Plants of varying height, and a skull cave for hiding
Food: Omega One Freshwater Flakes
fed twice daily
Thank you for all your help in advance.