Long Fin Leopard Danio Suddenly Died and Found with rigor mortis and a big black spot and abrasions on her belly

[finbean3]

We have a 55 Gallon community tank with 5 glofish danios, a long fin zebra danio, a short fin zebra danio, now one long fin leopard danio, 8 glofish tetras (blackskirt type), a glofish shark, 2 mystery snails (with babies on the way!) and 2 nerite snails. Here are the current water parameters (these are best estimates from testing kit):

PH: ~7.5

Nitrates: ~4ppm

Hardness: ~161.1ppm

Nitrite: ~0.5ppm

Ammonia: ~0.25ppm

KH:~89.5ppm

Water Temperature: 76ºF

 

We had 2 long fin (LF) leopard Danios who appeared to be doing well for a while (brought home beginning of September) along with the tank. (Started community/keeping fish for pets in July) They were included in a Medication Trio treatment that occurred on 9/29 to 10/7. Behavior seemed fairly normal, though I had noticed that the smaller of the two long LF leopard Danios had been hiding toward the bottom of the tank at night next to our shark who also like to hide lately. (I noticed a couple days ago after cleaning the aquarium that our glofish shark darted across the tank and started glass surfing. He calmed down when I responded with more food and rearranged his hiding place to be a little more seclusive.)

 

So just today, after feeding dinner and checking on the aquarium, I found our larger LF Leopard Danio floating listlessly and bent near our glofish shark's hideout. I have pictures and videos of the post mortem and the prominent issues I saw were: rigor mortis (curved into a C shape), a prominent black ring looking spot on her right shoulder, and abrasions on her belly. Please see pictures for reference.

 

I've run through a few scenarios in my head and the one that seems the most likely is a parasite infection. It has almost been a couple weeks and I'm planning to do a second round of paracleanse for the community based on Aquarium Co-op recommended treatment. However, I am a beginner (relatively speaking) at this and would love some input as to what others who have been at this longer than I have think it might have been that caused this sudden death. I was able to remove the dead fish soon after her passing from the aquarium and the water tests were after the removal. The smaller LF leopard danio is still hiding at the bottom of the tank and I'm watching her closely. Wondering if she is not feeling well either, but suspect it could just be because it is night time and she is the smallest fish in the aquarium. (And the newest. Her big store buddy just passed away too . . . not sure how she is doing) 

Thank you for taking the time to read.

 

 

 

 

Edited October 19, 2023 by finbean3
Added larger photos and removed a brand name.

[Colu]

What I would do as you have ammonia and nitrite is test daily and do a water change whenever you see any ammonia or nitrite and add a double dose of prime to help detoxify any ammonia or nitrite this what could have contributed to your fish death as ammonia and nitrite are extremely toxic to fish even in small amounts cut back on feeding to once a day and till you constantly see no ammonia or nitrite  fish start to decompose really quickly after death in warm water what your seeing on the body could be postmortem changes I would add a small amount of aquarium salt 1 table spoon for 10 gallons that will aid Gill function and add essential electrolytes and add some Indian almond leaves as they have antibacterial and antifungal properties and add an extra air I would focus on keeping stable water parameters zero ammonia nitrite and  Nitrate under 25ppm for now and monitor give an update in week if your still have issues@finbean3

Edited October 19, 2023 by Colu