Help With Neon Tetras Dying Please

[DrawsWithLight]

Hi all, I’m a new member but have been lurking for some time prior to my purchase of an aquarium and fish!

I have an ongoing issue with my Neon Tetras dying! I had them for just over two weeks and noticed on the Sunday morning a few seemed to be missing. I searched around the tank and found one of them in the plants, it had been dead for some time (pic below). I’m new to the hobby and I’m unsure how long it takes for a fish to decompose to this stage so can’t be sure when it died? Searching the tank further I found two more dead! Late that evening another Tetra seemed to be suffering and died later in the evening.



On the preceding Friday I added Microbe-Lift Special Blend and Thera P (Maidenhead Aquatics own products), and on the Saturday Microbe-Lift Plants Green. I also did a water test and there were 0 Ammonia, Nitrites and Nitrates. All fish seemed to be well.

I went to Maidenhead Aquatics on the following Monday, where I purchased all the equipment and fish, but they were stumped as to what has caused the sudden deaths. They did suggest the water temperature was a bit low at 22° and suggested raising it to 26°.

The following Wednesday another Tetra died.

I thought whatever had caused the deaths had passed but this evening, almost a week after the last death, another Tetra is showing signs of illness. This one has white ‘stuff’ towards the tail and is showing signs of stress.





As far as I can tell I’m doing everything correctly? The tank is a good size, 125l, with a Fluval 307 filter, with (originally) 12 Tetras and 6 corys and plenty of plants. The water is on the hard side but Maidenhead said this wouldn't be an issue. The plants are doing really well and I've not had any algae issues apart from some brown algae and bio film.

I’m using test strips to check the water conditions, I must say I’m not impressed with these as they don't seem very accurate, and I’m getting the following readings:

pH 7.6, KH 10-15, GH14

If anyone has any suggestions or have questions I’d be grateful. Pic of tank (before stocking) below for reference.

[LookoutTrout]

Hi and welcome.
Given you are using Microbe-Lift Special Blend I'm assuming this is a new setup that you added fish to straight away. Shops often advise this is ok but I expect the reason for your problems is your tank isn't cycled properly and can't cope with the fish load.
Try daily 50% water changes, feeding much less and buying a more reliable test kit as strips are known for being difficult and unreliable.

I had the same problems the first time I kept fish, I lost quite a few before things stabilised but back then I'd never heard of the nitrogen cycle.

[John Linklater]

Welcome. If you go to the guides section on this site you might find some helpful info in there. As well as the advice Lookouttrout gave you, you could try a different brand of bottled bacteria to help with the cycle. I use Seachem Stability but there are a few good ones. Maybe some more experienced posters could suggest some.

Good luck. It’ll get better

[Stephen]

Hi and welcome to the forum.

Sadly people often get poor advise from the local fish stockist (LFS). Some stockist are excellent, some not so good.
Firstly do not add any more fish for about 6 weeks.
Secondly reduce the temperature to 23C as this will be more ideal for Neon tetra and any Corydoras.
Thirdly purchase a liquid test kit such as the API Freshwater Master test kit (tests pH, Ammonia, Nitrite and Nitrate) and is more accurate than test strips.
Ammonia and Nitrite are toxic to all fish and must always read ZERO.
Fourthly buy a dedicated dechlorinator (a product that removes or neutralises Chlorine and Chloramine).
When doing water changes add the dechlorinator to the bucket of fresh water before adding the fresh water to the aquarium.

There are some excellent products that can help with the cycle (you are doing a fish-in cycle which isn't ideal).
Tetra SafeStart, Dr Tims One & Only and Seachem Stability are the recommended and proven "bacteria in a bottle" products. You only need one of these products and always follow the instructions on the bottle.
I would suggest doing regular (daily) partial water changes (30%) until the "bacteria in a bottle" product and liquid test kit arrives.

On a more positive note; Your aquarium is looking excellent.

All the best

[plankton]

Welcome to the forum.
As above....
It does sound like (and the pictures also point this way) the tank isn't cycled properly and you've added too many fish at once with the tetras and corys together.
Even with the "bacteria-in-a-bottle" products you can only use 6 small fish at a time, leaving at least 6 weeks between adding new fish.
Your water is hard, so that won't help with recovery for the soft water fish you have (no matter what the shop has said).
22C is the correct temp for neons and corys.
I have used the Maidenhead stuff and it's fine for topping up bacteria when you add new fish, but I'm not sure it actually copes with a brand new set-up.
It's unusual for an MA to give such bad advice, they don't get the "fishless cycle", but normally point out the low numbers of fish required to cycle the tank.
As above, daily water changes until you can get a good reading of the parameters.

[DrawsWithLight]

Thank you all for your useful advice. Seachem Stability and the test kit are on their way!

As expected, the Tetra in the photo was dead this morning. I'm a bit disappointed that MA allowed me to add all the fish so soon, the chap at York seemed quite knowledgeable! I did do quite a lot of research regarding setting up a new tank but I relied on MA for stocking advice and adding bacteria etc.I felt quite overwhelmed with all the information being fired at me at first, along with trying to find a decent tank/filter system and deciding on which plants and hardscape would be suitable.

After planting, the tank was left for two weeks (with the ‘quick start’ products added) before adding the tetras, then a week later the corys. I understood that the tank would take several weeks to naturally establish good bacteria but expected the Micro-Lift products to speed this process up?!

Can anyone advise how long the fish above had been dead for? I did wonder if it caused an ammonia spike which was then stabilised by the Micro-Lift products the day before I tested the water?

[DrawsWithLight]

On a more positive note; Your aquarium is looking excellent.

All the best

Thank you Stephen

[LookoutTrout]

Can anyone advise how long the fish above had been dead for? I did wonder if it caused an ammonia spike which was then stabilised by the Micro-Lift products the day before I tested the water?

I can't tell how long it had been, dead fish get picked at pretty quickly by other creatures in there.
I expect you'll never know the answer to your question, best thing is to not dwell on it and keep the rest alive. You're probably going to lose more but things will improve, cycling can take a few weeks.

[plankton]

It's just about impossible to know how long a fish has been dead for, it is unlikely that it was more than 24 hours, probably less.
The corys at least would have investigated as they are mainly carnivores, eating only a little veg in their normal diet.

[DrawsWithLight]

Thank you for the feedback. I changed the water yesterday, the test kit and Seachem are arriving today so will see what happens over the coming weeks!