Injury in my tank

[RockMongler]

I have found an interesting issue in my tank late yesterday after doing a water change, specifically a cooler water change.

One of my hillstream loaches (Beaufortia kweichowensis) suddenly appeared to have a fairly large wound on top of their head (was still red with blood when I first observed it a few hours after the water change), along with a moderate amount of fin damage.  I have gotten the individual moved into a hospital tank (2.5 gallon kit from walmart, with small power filter and an air stone) with aquarium salt.  However, I am kind of baffled as to what could have happened.

My tank is populated by white cloud mountain minnows, a single otocinclus, 4 total hillstream loaches (one is now in the hospital tank), a fairly large number of red cherry shrimp, malaysian trumpet snails, bladder snails, and a small assemblage of things like detritus worms, planaria, and hydra.  I am not entirely sure what could have caused the wounds (I haven't gotten a good chance with good lighting to get a good picture of the wounded individual).  Nothing in particular is known to be super aggressive and mean.  I'm not sure if it was a territorial spat between loaches or one of the whiteclouds getting nibbly.  From what I've read, the loaches supposedly don't have the right kind of mouth to nibble on each other, and fights are normally just 'topping' where they scoot around and determine their pecking order.  The white clouds have been a bit more rambunctious in their mating displays as of late, but that is almost entirely done in the middle of the water column, and it's usually  just the males flaring their fins and looking intimidatingly at one another (though a few of the males do have nibble marks in their fins, but it's not always the easiest thing to spot).  The otocinclus is usually super friendly, and i think has basically zero possibility of harming anything but algae and biofilm.  The snails and shrimp I think are in a similar situation as the otocinclus; harmless to any of the major denizens of my tank.

I wonder if the cooler water change (~65 F water into a ~72 F tank) just set off some slightly more aggressive tendencies related to spawning among my fish, and the one poor individual was in the wrong place at the wrong time, or if I should be more worried about returning them from the hospital tank to the main tank.  

Any thoughts?

[H.K.Luterman]

Is there any hardscape in the tank they could have accidentally bashed into while having a spat? I hope the little guy gets better soon and that this was just a freak occurrence. 

[DSH OUTDOORS]

My first thought is your hardscape moved while refilling the tank and he was just in the wrong place at the wrong time.  Maybe a rock or driftwood piece moved while your hillstream was under it.

Nothing you have in the tank seems likely to cause an open wound like you described.

This is of course, a guess without further information on how you do your water changes or what your tank looks like.

Just something to consider.

[RockMongler]

Just now, H.K.Luterman said:

Is there any hardscape in the tank they could have accidentally bashed into while having a spat? I hope the little guy gets better soon and that this was just a freak occurrence. 

The wound on top of their head could very well be them running into a rock.  I have some local stand stone that goes a good job of picking up lots of biofilm, and is a super popular grazing spot for everyone (but the WCMM who seem to only eat exclusively from the water column/surface).  

 

2 minutes ago, DSH OUTDOORS said:

My first thought is your hardscape moved while refilling the tank and he was just in the wrong place at the wrong time.  Maybe a rock or driftwood piece moved while your hillstream was under it.

Nothing you have in the tank seems likely to cause an open wound like you described.

This is of course, a guess without further information on how you do your water changes or what your tank looks like.

Just something to consider.

It was a fairly quick, and easy water change.  I use a plain ol' siphon to gravel vac/remove water.  I also mostly focus on easily accessible portions of the substrate for gravel vaccing during most water changes specifically to avoid moving hardscape too much for the exact reason that the hillstream loaches are super good at sticking to and hiding in weird little spots, and I also place repashy specifically in the more open spots.  The tank is a 20 wide.  The pile of cobbles on the right side of the tank is the most common place the loaches chill out besides the glass.  Later today when I get home from work, I should be able to get better pictures of the injured fish.  The thing that worries me the most was the fins having specific, fish mouth shaped and sized pieces missing.  

It being injured by a rock shifting around during the water change would make me less stressed in the long run, but still upsets me in the short term.  

[RockMongler]

Warning, images of wounded fish below.

 

I've gotten home from work today, so I can post a picture of the fish in question.

The tank is kind of a funny, almost superman logo shape, so getting a good picture and lighting is a challenge.  I wasn't able to get a good picture of them where I can see their damaged fin, but you can clearly see the wound on top of their head.  I will likely keep them in the hospital tank for a week or so for monitoring, and see how their healing progresses with aquarium salt as a treatment.