What now, complete restart?

So, I am disappointed in myself. After years of fishkeeping and sort of understanding the basics, I must have made some rookie mistake that led to a chain event that I am not sure the tank will survive.
Let me start when I think it begun -
10.3 I noticed one of my 15 cory cats had fungus in both eyes and missing barbels, other had missing barbels along with half its jaw or so. I took the one with missing jaw out, left the one with fungus or eye infection in the tank. Few days later the isolated one died despite medical treatment.
15.3 I noticed one of my male ember tetras, one of 40 pieces in the 360l tank, was thinner and bent in the stomach area. I took him out, put him in the quarantine tank, and after week of antifungal/antiparasitical medicine, returned him to the main tank good as new.
3.4 I saw the cory with the fungal eye and missing barbels at feeding time and decided to treat the whole tank with the same antifungal/antiparasitical medicine, in slightly lower doses, after water change, 3 day treatment. (obviously a mistake in hindsight)
7.4 one of fanning shrimp died, I assume as a direct result of the "safe for shrimp" medicine and 80% of hornwort shed its needles causing a large mess. I did a 50% water change, removed the plant as a whole, added limnobium to replace some of the plant matter and took out few stones and one large piece of wood.
Since then I did a bit more water changes than usual including a gravel clean, I used to do 30% every week, now I upped it to 30% every 5 days or so. I continued to feed the fish, the snails and so. I even tried adding more plants, though they didnt make it cause they were eaten by the snails.
This week I noticed the remaining two fan shrimp were forranging more on the substrate and filter intake sponge, so I fed a wee bit more to make sure they were fed, and included targeted squirts of crushed spirulina flakes in their direction. I fed in this week a piece of zucchini that stayed for 24 hours (which is normal, I keep carrots and bell peppers until they are eaten up to 48 hours, always a small piece and I do have 5 large snails) and a part of a leaf of a wild garlic, since its season started and other fish keepers here feed it too. It was eaten within few hours.
I obviously overfed or something, because today:
the corydoras with the bling eyes and still mostly missing barbels (it is fully blind, it doesnt scatter when I approach, but it is feeding normally) made an appearance, but there was a second corydoras, same condition, but rapid breathing, bloated belly and a smallish red dot on the underside. It is very passive but not overly so, swimming with others, retreating when startled. I also noticed one of the male ember tetras is again a bit skinny with sunken belly

I did a 30% water change and thoroughly washed the filter intake sponge and increased the main filter flow a bit. I will not feed until sunday and I added two 40cm pieces of healthy hornwort that I kept in other tank to grow to help leach the nutrients out of the water.
I dont expect the cory to survive this, obviously bad water quality or bacterial infection which indicates something in the tank is wrong.
As fate would have it, I have to leave tomorrow and get back on sunday, so if the fish dies, I will not be able to get it out of the tank.

Now I am considering what is the next step. Obviously the gravel should be cleaned again, I should also remove the small stones in the sand, on the off chance that the stones are causing the barbel injuries to the 3 corydoras out of the 15 I had in this tank for the past 6 months. I should also do a filter cleanup and ideally lift all the wood in the tank and clean under it. All of this cant be done at once or I will lose all the bacteria. The stone removal will also mean sifting through the sand and increasing detritus flow, which will lead to worse water quality.
Obviously something needs to be done in this tank I just dont know what and in what order to cause the least amount of damage. I cannot move the fish elsewhere, though in theory I have two smaller tanks that are empty and dirty so I could set them up, but with my workload maybe next weekend, maybe later. I could also perhaps take all the fish out, do the cleaning, follow up with mild filter clean, put 80% of new water in, give it 8 hours and return the fish. Though I am not sure how far to take it to not do worse with the cycle.

I did an No2 test after the water change, because I didnt consider doing it before, and it is zero.

Pictures and video of the fish, tank and gravel?

You can clean the filter and do a water change and gravel clean on the same day. It won't affect the filter bacteria unless you replace the filter media/ materials, and we don't recommend replacing them unless they are falling apart. Just squeeze the filter media out in a bucket of tank water and re-use the media. If it's really dirty, use 2 buckets of tank water, clean the media in one bucket and then the second bucket. Tip the dirty water on the lawn.

1) Wipe the inside of the glass down with a clean sponge.

2) Clean the filter.

3) Do a big (75%) water change and gravel clean the substrate.
Make sure nay new water is free of chlorine/ chloramine before it's added to the tank.

If you don't have a gravel cleaner, buy one or make one from a 2 litre plastic drink bottle and a garden hose. If you need directions on making one, let me know. It's pretty simply, just cut the bottom off a drink bottle and shove a hose in the top.

Hmm. We're like medieval peasants diagnosing our tanks. But I see the possibility of 2 things.

The Corydoras seem to have a bacterial disease. That red patch usually says that, and there isn't much to be done. I would remove him to a holding set up, to limit the spread if you can.

The embers are a worry. Thin and sunken has two common causes - one is gutworms, which can be treated with praziquantel. They all have them, but the sunken ones have begun to lose out when for whatever reason the worms proliferate. There's hope it's something that simple because the one you isolated responded..

Option two is Mycobacter infection - fish tb, the bane of the fish farms. This bacteria is incurable and untreatable. It survives bleach. And it's very common, usually kept in check by the fish whose lives are considerably shortened by it. If there is an outbreak, it generally flares up via fish eating dead fish. Do you think the Corys could have found a dead ember?

"Myco" is controversial, because it's a bacteria that shows itself in so many ways it becomes hard to pin down, and you can only confirm it in a dead fish, via an autopsy. Studies have shown it to be common in fish raised in intense crowding, but the aquarium business doesn't like to discuss it. In extremely rare cases, humans can catch it from fish (I did, it's cured, but that's why it interested me enough to learn about it), so it causes a bit of panic sometimes. There are many more things you can get from a cat or dog than this one uncommon transfer from a fish. But it is a fish killer that can show 3 or 4 years after you buy a fish. I just assume every farmed fish has it, and take it as it is. I leave no deads in tanks and tend to euthanize any deformed fish if the deformity develops in a previously healthy fish.

Took a quick pic of the tank

I did a glass clean on the 10.4 and gravel clean this saturday, 16.4 though only did 50%, cant do all at once. Last time I did clean the filter intake sponge was january, the full filter clean was done in december. I usually do them every 6 to 8 months, since it is a large Eheim and I have a very large intake filter sponge too.

The medicine I used before was https://www.eshalabs.eu/europe/products/esha-2000supregsup.html, which should have caught parasites', though not sure if internal ones. Could have been some remnants are in the gravel, but I dont feed bloodworms and nothing live, should be safe from reproduction and the three day cycle should have cured all of them. Who knows if it is not the same one.
TB is always a concern.

I will go count the tetra and try to take a picture of it to see if any was missing and/or eaten. The only thing that could have died in the past 6 months was the marbled hatchetfish, had 15 in the beginning, only have 8 now and I only saw 2 bodies on the top floor dried out, rest just poofed. But it has been 8 the past 3 months now.

Ok, roughcoutned 40 tetras, they should be in the initial numbers. Tried to take a picture, the fish wont stand still at all, so no good quality

Just found this article, I could try this, I think I have a good chance of catching this particular fish and I do have a 1l place I can put it in. I have no other place to quarantine to not infect other inhabitants, so would have to return to the main tank or humanely kill it

let me know your thoughts

Came home, the cory is still the same though slightly less bloated, but one tetra dead. Must have been recent, still had decent color and was on the surface so hopefully nothing ate it yet. Will try to find time tomorrow to do a 50% water change with sand clean if possible.
Really hope is not tb

It was ofcourse premature, the fish died overnight and the body was lodged in the worst accessible place for me so had to lift a lot of stuff. Used this time to scoop out some of the stones, really not at all sharp to touch, and do a 50% of water change with gravel clean.
I also spent time observing the tank, i have 13 remaining cories. 12 of them have real long barbels, good color and white bellies, no scratches or anything. One, the blind one, has no barbels and a small red dot near pectoral fin, but good color and is eating with the others.
I guess only time will tell.
The snails didn't appreciate the no feed period, had to shake them off a lotus bulb and give them some greens.
Since i have some wood in the tub, when it soaks i will take stuff out, do more of the stone removal and better gravel clean and will see i guess.

Filters should be cleaned once a month. If there is a lot of gunk in the filter, the aquarium water will simply be filtered through gunk and this can encourage external protozoan and bacterial infections.

Dirty filters, dirty gravel, dirty glass, and lack of water changes, cause a lot of fish health issues.

The first thing I recommend when people have sick fish is to clean the glass, filter & gravel, and do a big (75%) water change every day for a week. Quite often this will fix a lot of issues. Even if it doesn't fix the issue, it provides a cleaner environment for the fish to recover in and for medications to be used in.

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The cloudy eye on the Corydoras can be water quality related or a physical injury. Cleaning the tank up might help if it's a water quality issue or minor infection.

The red patch on the Corydoras is an infection, most likely an external bacterial infection. Salt should treat this, (see directions below for salt).

The skinny tetras probably have intestinal worms. Feed them 3-5 times a day for a few months so they can hopefully produce enough blood until they are treated for worms.

Section 3 of the following link has information about treating intestinal worms in fish. Use Levamisole or Flubendazole first because thread/ round worms are more common than tape/ flat worms.


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SALT
You can add rock salt (often sold as aquarium salt) or swimming pool salt to the aquarium at the dose rate of 1 heaped tablespoon per 20 litres of water. If there is no improvement after 48 hours you can double that dose rate so there is 2 heaped tablespoons of salt per 20 litres.

Keep the salt level like this for at least 2 weeks but no longer than 4 weeks otherwise kidney damage can occur. Kidney damage is more likely to occur in fish from soft water (tetras, Corydoras, angelfish, Bettas & gouramis, loaches) that are exposed to high levels of salt for an extended period of time, and is not an issue with livebearers, rainbowfish or other salt tolerant species.

The salt will not affect the beneficial filter bacteria, fish, plants, shrimp or snails.

After you use salt and the fish have recovered, you do a 10% water change each day for a week using only fresh water that has been dechlorinated. Then do a 20% water change each day for a week. Then you can do bigger water changes after that. This dilutes the salt out of the tank slowly so it doesn't harm the fish.

If you do water changes while using salt, you need to treat the new water with salt before adding it to the tank. This will keep the salt level stable in the tank and minimise stress on the fish.

When you first add salt, add the salt to a small bucket of tank water and dissolve the salt. Then slowly pour the salt water into the tank near the filter outlet. Add the salt over a couple of minutes.

Your tank needs a picture on the back and some floating plants to make the tetras and hatchetfish feel safer more secure.

My tank is standing in the middle of the room and thus is seethrough, no problem with that. I will add a smidge more hornwort, but in a week or so, it will again look like this. There are the cryptocoryne leaves on the surface, some floating riccia, limnobium,... I have to remove quite often to keep some part of the surface clear.
I did a nitrite test, it was not zero which surprised me. I did clean the filter, though I have no idea how you clean a 6l canister filter every month. It took me an hour and I cant restart it again, have to connect a hose and connect it to the intake and push a stream of water to restart the filter. It is a lengthy process.

I also cleaned glass, but I did gravel clean yesterday, so I only did another 40% water change and collected all the plants that did not look super healthy to prevent the decomposition.

Is it possible some food can cause this? I used a dajana spirulina tablet yesterday

Will do another nitrite test tomorrow and will see

A sidenote, is it possible the test was not zero because I fed about an hour before that some amount of dry food? Could it be it was not yet processed, or is it always supposed to be zero, no matter what?

Uneaten food can cause ammonia readings, and you can get an ammonia reading if you test the water straight after feeding, or if you put a lot of food in the tank. It can take the filter bacteria an hour or more to process the ammonia from feeding and you might get a low reading during this time. However, it should be 0ppm an hour after feeding if the filter is established and working correctly.

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After cleaning an external canister filter, set it up wherever it normally lives and put the intake hose in the aquarium. Put the outlet hose into a bucket next to the filter. The filter should be empty and turned off during this process.

Suck on the outlet hose for a few seconds to get the tank water draining into the filter. Then put the end of the outlet hose into the bucket. Let water fill up the filter and start flowing out of the outlet hose and into the bucket. When water is flowing into the bucket, put your thumb over the end of the outlet hose and put the hose in the aquarium where it normally goes.

Dry your hands. Turn the filter on and it should start running. You can give the filter one or two gentle rocks from side to side to help remove any air bubbles in it. Then it should be working normally.

If the motor does not start or pump water out properly, then it could be a damaged impellor, broken or worn impellor shaft, or the motor unit is failing.

With a bit of practice, you should be able to clean an external canister filter in 10-15 minutes.

@Colin_T would you agree that virtually everyone over feeds their fish.

itiwhetu said:

@Colin_T would you agree that virtually everyone over feeds their fish.

Click to expand...

Yes, including me

Most fish are fed more than they need. I fed mine heavily because I was breeding them and they need the extra nutrition to develop good gametes. But my fish were a bit overweight.

There is nothing wrong with feeding the fish well, but they should be fed a variety of good food and maybe have one day a week without food.