Single Dying Fish every 2-4 weeks

[2332fun]

Hey guys, I've been running a 55 gallon live plant/fish tank for almost a year now. It has been one heck of a bumpy ride to get to the point I'm at currently with the tank.

My set up is:

55gal tank
2 heaters on opposite ends (both set to turn off at 78 degrees)
70 gal fluval filter set to low
2 air stones on opp end of filter for circulation
fine gravel substrate
plastic line to keep the frogbit from drowning under the filter's waterfall
2 driftwood (both soaked and rinsed before put in)
2 coconut bridge shaped hides
1 coconut dome hide
over 10+ species of plants (including java moss, amazon swords, amazon frogbit, java fern, and others)

The inhabitants:
a plethora of snails that hitchhiked on some plants
cherry shrimp (~10)
albino corydora (5 down from 6)
panda corydora (6 down from 9: had a successful breeding at one point)
julii corydora (1 down from 5)
ember tetra (14 down from 15)

I lost an albino corydora months ago to a red bacteria, but was able to cure and save the others with quarantine and antibiotics.
I lost two panda to some whisker shrimp that were sold to me as juvi ghost shrimp months ago. (said whisker shrimp have been passed on). I lost one panda corydora yesterday with no symptoms of anything.
About every 2-4 weeks I have lost a julii corydora with little to no symptoms of anything. Two of them had a yellow-ish spot on their underside, while the other 2 had no marks of any sort.

My routine is to rinse the filter with tap water (squeezing the sponge and lightly rubbing the other 2 media) every Tuesday. Every thursday I do a gravel vacuum/water change of about 1/4-1/3 of the tank. I feed the tank 2 algae wafers (nickel size), about 6-8 sinking pellets, and a super small pinch of flakes every Monday, Wednesday, Friday.

My "API freshwater master test kit" has found my water parameters to be as follows (2 days after a mechanical filter change and 1 week after a 10 gallon water change):

pH (used high range pH to read): 8.2
Nitrite: 0ppm
Nitrate: 5ppm
Ammonia: 0ppm

I realize my PH is high, but that is because of my tap water, which remains 8.0-8.2 pH and because of such, I believe my fish have mostly adapted to its alkalinity.

During the water changes, I use:
API Stresscoat+ 25ml
Tetra AquaSafe 50ml
Tetra AquaSafe+ 25ml
Tetra EasyBalance+ 50ml
Seachem AmGuard 5ml
Salt&Fresh Microbe-Life Nite-out 2 starter bacteria 25ml

I make sure to not use lotion or soap the morning before doing the water change, only rigorously rinsing my hands in tap water to keep contaminates out of the waters.

My fish show no signs of stress: my shrimp graze on the plants, my snails proliferate like wild rabbits, my tetras swim in a school everywhere around the tank, and my corys sift the gravel together and occasionally rush to the top for a bubble before swimming around again (I like to call it their zoomies). There is no gasping for air, no bloating, no floating on their sides (til death), and no weird markings, cuts, scrapes, or rot.

Attached are two pics of the aquarium as of today, and two pics of the julii corydora that showed symptoms of its death 2 months ago.

Please help me figure out what's killing my fish before my community falls apart!

 

[Aiken Drum]

I think if was something serious with the tank you would be losing more than 1 fish every few weeks.

The only fish you really appear to be having a problem with is the panda corys, and these seem to be difficult fish to keep (but thats not my own personal experience).

Perhaps water quality historically wasnt as good as it is now (eg during cycling) which could have led to some issues that led to a shortened life span which is now manifesting.

I would say thats an awful lot of chemicals going in the tank, which cant be all that be good for things. Most of them do the same thing. You are using 3 different dechlorinators. Pick one (ahem Seachem prime). The amguard? You arent seeing ammonia so you dont need that. Easy balance? If you keep up with your water changes you dont need this. It also "stabilises" water, and trying to chemically alter water parameters almost always causes more problems that it fixes. Microbe-Lift Nite Out? Thats bottled bacteria, if you are cycled you dont need that.

If nothing else, cutting out all the chemicals will save your pocket. As long as you are doing your water changes all you need to be adding to the tank at water changes is dechlorinator.

 

[2332fun]

@Aiken Drum: Thank you for the quick response! I was worried my bacteria might be low as when I do water changes/gravel vacuuming, I tend to go deep into the substrate and I was worried I was disrupting the good bacteria (plus I just replaced the sponge part of my 3 layer filter).

I'll try going to just the one dechlorinator, but my stores don't have seachem prime. Which of my current products would you say is the best cover-all? Should I still use the stress-coat+ btw?

 

[Aiken Drum]

Is there a reason for the deep substrate gravel cleaning?

If you are doing a deep gravel clean regularly, then you are removing beneficial bacteria, but it isnt getting chance to re-establish. So the next time you do your deep gravel vac, you are hardly removing any bacteria. Consistency is key with gravel vacs. Do them regularly, there is very little beneficial bacteria established there to remove (it will establish elsewhere were it isnt disturbed). Do them infrequently and you can then disturb the balance. If you are doing gravel vacs, either do them frequently, or if you do them infrequently, dont do the whole substrate surface in one go.

As to a recommendation on dechlorinator. My recommendation would be to use whichever works out the cheapest price/water change. That usually means either Seachem Prime or API Tap Water Conditioner. Forget all the bells and whistles of slime coat this, or ammonia detoxifying that. A water conditioner is a water conditioner. Get what does the job of removing chlorine at the lowest price/water change.

Of the ones you have, the only one ive personally used is stresscoat, it works just fine, the same as any other water conditioner. But its stupidly expensive. I switched to prime based on cost, with no adverse issues, and its generally considered the best water conditioner (i think i read its used by 60%ish of fishkeepers). If you cant get Prime from your LFS then buy it online. I wouldnt add stresscoat alongside another dechlorinator, but if thats the one you decide to continue using, then just stick with it. Its a good dechlorinator, you dont need the aloe vera/slimecoat additive though, its just a marketing gimick.

 

[2332fun]

@Aiken Drum I only vacuum one side of the tank at a time; for example, this week I will be doing the far right 1/3 of the tank, then next week I will be doing the center, then the following I'll be doing the far left 1/3 of the tank. I rotate my gravel vacuuming and have to do deep cleanses because each time I do it, there's a bunch of brown gunk that gets pushed up when the hose touches the substrate. It's especially bad around the bases of my hides and rocks, where the water flow is non-existent. I was worried that my corys were dying from the filth they push up with they shuffle through the substrate.

I will try switching to the API stresscoat + only from now on and see how they do. Should I still stop putting the niteout into the water after changes since I do such a thorough gravel cleaning?

 

[Aiken Drum]

If you are cycled you dont need to dose bottled bacteria. One thing i noticed is you rinse your filter with tap water. The chlorine in the tap water is more of a risk to killing off bacteria than your gravel vac is. Use water taken from the tank or dechlorinated tap water.

 

[2332fun]

So I skipped the water change yesterday and didn't add any chemicals due to time constraint with homework, and found another dead panda hidden by a rock. I lifted up all hides to make sure there weren't any other dead bodies. Similar to the other corpses from before, there were no markings on its body to show what it died from. My pandas were at best a year old, is this still probable from old age? @aiken drum

I found one of my smaller albinos with a tiny scratch on his side, and I think his tail fin is slightly missing part towards the bottom of it? I noticed during feeding time he was staying towards the middle of the tank rather than eating at the bottom with the others. Three of my albinos have gotten much bigger than the rest. Is it possible these 3 big albinos have recently been bullying my other smaller fish due to size differences? Pic is of slightly injured albino (now in quarantine tank for observation) and of feeding group to show size difference.

My tetras have not had any decline in numbers (still at 14). But my juliis are down to 1 and pandas down to 5 (thought it was 4 but caught one hiding in the back), so I'm hoping I can get this sudden death to stop.

 

[Aiken Drum]

My pandas were at best a year old, is this still probable from old age? @aiken drum.

Corys live well beyond 1 year. Im not too sure on their max age, ive read 3 to 4 years, ive read 7 years +. I have panda corys that are over 3 years in age.

It certainly looks like the issue is cory related rather than a tankwide issue. I dont have problems with corys, other people do.

In the wild corys live in acidic water, so maybe your high pH isnt ideal for them. Fish do tend acclimate to a wide range of pH levels, especially tank bred fish. Maybe you pH is pushing it too far? I wouldnt go adjusting pH though, it tends to cause more issues than it solves. If you are having issues with a particular fish in your tank, it might be better to look at different fish. I would stick at it for now though. See how things go, if you get a new batch of corys, possibly try from a different store. Maybe now your tank is more established the deaths will slow down.

 

[2332fun]

So an update this morning: I have huge clusters of eggs everywhere and my larger albinos are more active than ever! I'm wondering if the deaths were from hormonal territorial mother fish behaviors ? While I saw no injuries, maybe the moms were chasing other fish around and stress killed the chased fish? Grasping at straws but this is a Lot of eggs lol! Covered up a batch toward the bottom with some plants but I've got no setups or nearby fish stores so it will take too long to get supplies in to properly raise them. Here's to hoping for baby fish!