Zebra Danio...

[supersuzie]

i have 4 zebra danios, 2 males and 2 females. they all seem very happy, always darting around the tank chasing each other and they feed very well. in fact, they are always hungry! i noticed yesterday that one of the females has a dark spot on the side of her belly. it is flat against her skin and not raised. it looks like she just has a couple of dark scales but i've never noticed this before. we've had them for nearly three weeks and they have the run of the tank themselves. the water is as follows
pH: 7.4
ammonia:0
nitrite:0
nitrate:10 mg/l
kH:3-6
gH:very low (added some calcium carbonate rock to right this)
tank temp: 25 C/ 76 F

the pics are from video stills as they just dont keep still long enough to get a good pic.

any ideas as to what this is and help to sort it out will be greatly appreciated

ss x

 

[The-Wolf]

really hard to tell but looks like a bruise
it should heal on its own in a few days.

I'd add some melafix just to help prevent any secondary infection

 

[supersuzie]

thanks for the reply. after watching the affected fish more closely, she seems to be getting picked on by the other female, so you're probably right about it being a bruise. i got some melafix (it smells great!) and i'm doing the injury treatment and we've just put in a group of glowlight tetras which seems to have broken up the bullying...for now! i'll keep you posted!
ss x

 

[WILDER]

Good luck.

 

[supersuzie]

bump.

ran the melafix course for seven days then did a 25% water change. the spot hasnt got any bigger but it hasn't gone away either. she still seems fine and the bullying is still better since the tetras arrived. none of the other fish have any symptoms of anything and i fed them peas just in case it was internal, but they are still fine. a bruise wouldn't take this long to go away would it? its ten days sine i first noticed it.
any ideas or should i just chill out if all the fish are fine every other way?