Please Help: what could have caused this injury...


New Member
I have a 60 gallon tank that finished cycling a week ago and last Sunday i added in a clown fish, yellowtail damselfish and a firefish, and they seem to get along just fine, no bullying etc.
Anyways, yesterday morning i woke up and noticed there was this white looking circular bump on the side of my firefish, but the middle of the bump was indented like a ring. You can see the bump front on, but if you look at it side on, you can see the indent. Despite this, the fish was swimming around fine and still eating...
But then as the day went on, he stopped swimming around as much, and started hiding behind rocks etc... occassionally coming out into the open and then going back into hiding again. When it was hiding, i started noticing that about every 10-15 seconds it would twitch its tail violently, as if it was shaking it - but i didn't notice it scraping itself against rocks etc. At night, i tried to feed it again to see if it'd eat, and this time it wouldn't.
Really late last night, the fish died =( But when i picked it up out of the water, i noticed the white bulge with the indent was gone, and instead it was replaced by a red patch, it kinda looked like a bruise, or red spots under the skin.
I tested my water and it was at salinity:1.023, ph:7.8, ammonia:0, nitrite:0, nitrate:0, KH:9-10, temp: 80-82
I've attached two photos. The first one was taken at the beginning of the day, you can sort of see the bump, but i couldn't get one on the side cuz it just came out as white. The second photo was taken about 5 minutes after the fish died, the purple-ish color around its head only appeared after the fish died, but you can kinda see the red i mentioned.
Does this sound like it could be an internal/external parasite? Or it was attacked? Or it hit something? Or... something completely different? What do you guys think? I'm kind of confused as to how the 'bulge' just disappeared, leaving no signs of any loose skin or cuts etc
Please help! I'm planning on getting another firefish, and really don't want the same thing to happen again.. or to any of my fish...
Edit: About the damsel - I thought it could be my other fish attacking it, since i've had damsels before when i was overseas, and that one always nips at fins. so i've been observing the behaviour of this damsel, but it seems really timid compared to the ones i've had previously. It tends to be scared of the clown and i haven't seen it being aggro with territory.. well, yet. The firefish was always out in the open swimming around the damsel, until yesterday when it got injured. Are damsels so evil to 'act nice'? :O
On a side note that i forgot to mention, there's this 6-7inch (at least) worm in my tank, 5-6mm in diameter, brown.. it doesn't have any visible bristles, the skin is really bumpy or freckly. Anyways, whenever it moves, it suctions itself onto the surface and then pulls itself along the rocks/gravel. It doesn't move in a bell curve or anything, just flat along the ground. And i think it stretches and shrinks. Could it be possible that the worm suctioned itself onto the firefish while it was by the rocks. That was my first thought when i saw it actually, because of the shape of the injury, and the indention in the middle...



Active Member
There are a number of possibilities here (tank being new and adding fish so quickly, new fish stress, acclimation, disease, etc.). Just to make sure it's not something with the tank, I would not add anything right now. Give it 2-3 weeks to stabilize.
Sidenote...I would get rid of the Damsel. I didn't include this in the list of possibilities above, but I would be highly suspicious of this being your culpret. They are evil.


Could be a ton of things and wait a little bit before adding anything else back into this tank as the poster suggested above.
I would bet money that the damsel probably nipped the firefish, which probably already had an issue and that did it in.
this is why you need to quarantine everything!


Staff member
Its hard to tell exactly, but usually aggression will not result in a bulging bump, and will cause breakage of the skin.
You have a new tank. I'd leave well enough alone for now and not add anything else for at least a month.
In the meantime, you may want to think about setting a permanent quarantine tank. Introducing fish directly to the display tank can end up in the introduction of diseases to your system.