Is My Fish Sick Or Being Bullied?

[pugwash666]

I have never looked after fish before,but our neighbour who was leaving(financial troubles)gave us his 3 platys(his teenage sons were going to flush them down the toilet).He has kept his large tank with him,so we had to buy a tank pretty quick to home them,this is what we brought http/www.rocketaquatics.co.uk/fish-frf44...arium-p-51.html .. .We filled with tap water and added anti chlorine solution.We left it a few hours before we put fish in,they were all swimming about active and lively,and have been for the past 2 weeks.But the last few days we have noticed one of the fish seems to stay in the corner at the bottom of the tank,and the other 2 seem to bully it,chase it whenever it moves from that particular place.This fish was always the most active and lively one,but now does not seem to move much(swim about).I do not know if it is sick,or is it because the other 2 seem to be ganging up on it.When we had him he seemed nice and red/golden,but i cannot be sure,but it seems to have black on him(spot on tail,flecks on back).Any advice please.

 

[Spishkey]

my advice is............
well for a start your tank is probably not cycled. have you been doing any water changes? if not your fish will be suffering from ammonia poisoning by now and will probably die rather soon. the best thing to do now is a water change (i personally would do a 50% change)
you NEED to get yourself a water testing kit to check the levels of ammonia nitrites and nitrates in the water
ammonia and nitrite need to be at 0 in a fully cycled tank
no idea what im on about?

have a look here, this may help you..........a lot!!

<a href="http/www.fishforums.net/content/New-to-t...eady-have-fish/" target="_blank">http/www.fishforums.net/content/New-to-t...eady-have-fish/</a>

also in regards to the black 'spots' these are very possibly ammonia burns which are healing. the bullying could be caused by a number of things. you may have all males which will fight, you may have two males and a female (the males will still fight) ideally for them to get along you would need 2 to 3 females for every 1 male

females look like this (note the fan shaped bottom left fin)

males look like this (note the bottom left fin is more tube like)