Tail Rot Vs Aggression

[drtmima]

I gave a 600L aquarium, bought 1 month ago second hand from an informed hobbyist who was upgrading. The tank included 1.5 yr old active filters, equiptment, plants and 30ish small community fish - mostly tetras & livebearers. I'm doing 30% water changes weekly, ammonia/nitrites 0, water temp fluctuates from 82F in am to 86F in pm. (100+F outside temp) I have lost 4 fish so far: a lonely coryduras who seemed healthy but just disappeared after 2 weeks, 2 guppies, 1 penguin tetra. The penguin was definitely sick for a few days, not wanting to eat, breathing heavily, it also had a horizontal split in his tail fin & lower half was eaten away. I had him in a mini hospital tank for 3 days before he died. All the fish are very active, the penguins (school of 9 now) are constantly chasing each other & the one who died was definitely the smallest. There was no white edge or discoloration of any fins. Now 1 other penguin has a small split in his tail, no sign of fungus. The 3 female guppies all have raggedy edges to their tail fins only with no fungus edge but are active & eating and the male guppy has beautiful fins. School of 7 red phantom tetras, 2 large redeye tetras, pleco, 3 mollies & 2 swordtails all seem fine. 1 lonely neon tetra lost a fin below his gill last week, the area is slightly red but he is swimming fine & eating well.
So I am wondering what is going on - could my peaceful community fish actually be having aggression issues? Or do I have some underlying bacterial disease going on? My tank is very large for the small number of fish, my water seems clean, but maybe they had some disease issues previously explaining the weird ratio of guppies (a few large females & 1 small male, oh yeah the only fish I lost during the move itself was a guppy), and the lonely neon & coryduras?
I am also wondering if there is anything to do about my water temp. I know it is a little high, & that the fluctuation is not good. But it is very hot here even at night, and the tank heats up daily from the aquarium lights & also from the high outside temp.
Any advice is greatly appreciated.

 

[Louiseness]

Those 2 redeyes would be my first suspects. Its likely that they could be getting nippy because they aren't in a proper school. The phantoms might be worth keeping an eye on too.

I'd lean towards nipping rather than finrot just because the of what you said about fins just 'going missing' rather than slowly disappearing.

 

[Athena]

I agree - keep an eye on those red eye tetras as some are known to fin nip, even though they are classed as peaceful tankmates.

To prevent the fin damage becoming infected in any way, you could use an antibac medication from now to prevent secondary infections developing and to help in the healing process. Obviously, lots of regular water changes help to repair fin damage but if the damage is due to being fin-nipped, then this will be causing stress to the fish - and that is enough for secondary infections to develop.

Athena

ps - forgot to add that if the fish are also stressed due to the high temp, this can cause them to behave differently, which may be why the tetras are fin-nipping. Keep the tank lights off to reduce extra heat - and increase your aeration if possible as the higher temps will decrease the amount of oxygen in the water.

 

[colleen0309]

You can fill a pop bottle with ice or ice water and float it in your tank to help lower the temp. Believe me, I know how you feel. My tanks (all 7) were running between 84 - 86 F. My fish were not impressed. My husband went out and bought an air conditioner. Now the tanks are staying at 74 - 76 F.

 

[drtmima]

So this morning it looks like another penguin has a tiny rip in his tail & the neon has a chunk missing; I am assuming it is the heat/aggression/stress thing for now because (correct me if I'm wrong) the tears are all in the tail & the fins are fine, and the affected fish don't seem sick. Fin rot makes them sick?
I like the floating ice bottles idea, will start today. But I think I need the lights on for my plants. And is it worth it to medicate for secondary infections - how do I do this without killing the good bacteria & my plants? Thanks for your quick replies!

 

[Athena]

If you use something like Waterlife range, they don't harm your beneficial bacteria if used in the correct doses. Stressed fish can go downhill very quickly, so I would say it's worth using the anti-bac given there are so many of them suffering with fin damage and heat stress.

As for using icepacks in the tank - be careful with this because it can cause such a sudden fluctuation in the localised temp that this in itself is enough to shock a fish and cause sudden death. You can imagine how freezing cold certain areas of the tank water will become (nearest to the ice pack). Perhaps if you position it in the path of the outflow pipe of the filter (but not right next to it) it might help combat this, so that as the ice cools the water it is dispersed throughout the aquarium, rather than it sitting in a quiet area of the tank that doesn't get much water movement. If the water is that warm, no doubt the ice pack will melt soon enough though, so you will prob need a good supply in the freezer LOL

Athena

 

[drtmima]

Yeah my 2L ice bottle melted in 1 hr, and I put it near the outflow for that same reason. What is the waterlife meds? Active ingredient? I do not live in USA/Europe so finding a specific brand may be challenging. Thanks again!

 

[colleen0309]

If you use something like Waterlife range, they don't harm your beneficial bacteria if used in the correct doses. Stressed fish can go downhill very quickly, so I would say it's worth using the anti-bac given there are so many of them suffering with fin damage and heat stress.

As for using icepacks in the tank - be careful with this because it can cause such a sudden fluctuation in the localised temp that this in itself is enough to shock a fish and cause sudden death. You can imagine how freezing cold certain areas of the tank water will become (nearest to the ice pack). Perhaps if you position it in the path of the outflow pipe of the filter (but not right next to it) it might help combat this, so that as the ice cools the water it is dispersed throughout the aquarium, rather than it sitting in a quiet area of the tank that doesn't get much water movement. If the water is that warm, no doubt the ice pack will melt soon enough though, so you will prob need a good supply in the freezer LOL

Athena

Thank you Athena. I forgot to mention putting the pop bottle at the filter outflow. I use zip strips to keep it in place.