Hello, I woke up to find one of my albino cory dead. On a closer examination it reminded of a scene from alien. The stomach had a hole and its insides were missing. Does anyone have any idea as to what could cause this?
Ph 6.8-7 Ammonia <0.25ppm Nitrite 0ppm Nitrate < 5ppm 90 litre tank, freshwater, 24 deg C, Internal filtration with ceramic tubes, bio balls, sponge, charcoal and a phosphate removing substance. Established for 2 months, it was a tank upgrade Last water change was 10% yesterday Tankmates: 3 emerald cory 4 black cory 1 albino cory 5 zebra snail 3 amano shrimp 6 rummy nose tetra 10 neon tetra I last added 2 weeks ago - some plants, since this i have found two tiny what i believe to be trumpet snails which have been removed, also the zebra snails and a piece of mopani wood were added then. 7 days ago i treated for fin rot as i noticed a couple of my neon tetra were showing signs of tatty tails with a white cloudy look at the ends. I followed the instructions and left the tank alone (carbon removed from filter ) for 4 days then done a 25% water change. The neons have all been cured. Back to beautiful looking fins. Substrate is fine sand with some flourite black in the plant pots. All the fish and plants seem to be healthy and eating. I feed frozen food twice a week and flake/ pellets the rest.
I'm assuming, if there had been a wound/ulcer-like marking on its underside, you would have noticed when it was alive? One possibility is that, if this had existed, it might have burst (bacterial-type infection) and the infected part inside come out with it.
However, I think the much greater likelihood is that the fish died for whatever reason, then the shrimp (and possibly other fish, especially the cories) set to work on eating it. I've seen pictures / videos online of shrimp managing to scoff a dead fish, and leaving nothing but its skeleton, within 2 hours.
For now, I would do a water change up to 50% irrespective of the good water quality (as this may help get rid of other toxins not detectable/measured by home-based water testing kits including stress hormones), keep a close eye on everyone for the next few weeks to ensure no signs of bacterial-type infection including another episode of finrot or wounds/ulcers, keep water in optimum condition at the levels it's currently at, and be ready to treat with medication if required.