Fish Injured?

[Cirus]

Hi, i came home from work today to find one of my 2 swordtails injured or something. It kind of looks like its fin has been bitten?. Heres a pic anyway, any help appreciated thanks . http/i3.tinypic.com/30uws2v.jpg

Just read the read before posting thing sorry . Just have to add that i have a 90litre tank thats a week old and i only have 2 fish in there, being a male and female swordtail. I also havent done any water changes yet.

 

[pumaf1]

did you cycle the tank?

 

[karmagl]

My advice is to do a water change and maybe add something along the lines of melafix just some bacterial stuff so it doesn't get infected

 

[Cirus]

Thanks for the replys, it died last night unfortunately . I did a 30% water change last night and the male swordtail seems to be ok. Im just wondering if anyone has any idear what the injury actually is?, to me it looks like the fin was a bit chewed but i dont know much . Could it of got the injury from the filter or something? becuase i was told sword tails were peacefull fish. This injury happened within the period of like 8-9 hours, she was fine in the morning when i fed them. I saw the male sword tail like like nip/suck the side of the female a few times before, but didnt seem to be doing any damage.