shrimponablimp shrimponablimp
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  • Posted on: 25/8/2018 20:02
Urgent help needed; nearly all fish dead and I have no idea why #1
Tank size: 54l
Filter used: Marina i160
How long has the tank been set up?: A year and a half.
Water parameters:
pH: 7.0
Nitrite: 0ppm
Nitrate: 0ppm
Ammonia: 0ppm
Temperature: 26 degrees celsius.
Current population: 4 neon tetras, 2 amano shrimp.

The last water change was two days ago and I replaced 10 litres.

The tank was cycled and I bought the fish gradually, and chose fish which would live well together. The largest population was 3 albino cory catfish, 6 neon tetras, and 4 male guppies, but it took a few months to get there. There were no deaths for about a year and a bit, but a few months ago I started having deaths every few weeks. The most recent being I came home today and saw the last two male guppies had passed away.

We've taken action over these months such as more frequent water changes, monitoring the temperature more closely, keeping an eye on the water parameters, looking for signs of disease, removing plants when we thought they were causing too much debris, using filter-aid to boost bacteria, making sure the filter was maintained as well as possible etc. We spoke to someone in a pet store and they said it just happens and that it could be temperature related what with the heatwave. So the heater isn't on anymore.

I really don't know what to do. It wouldn't be so bad if I knew what was going wrong as I could fix it, but as I don't know I don't want to buy any more and risk more lives. At this point I'm wondering if it'd be better to just look after these tetras and shrimp the best I can and get rid of the tank afterward.
Does anyone have any idea what could be going wrong here? Thank you.
fcmf fcmf
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  • Posted on: 25/8/2018 22:26
Re: Urgent help needed; nearly all fish dead and I have no idea why #2
What is your water hardness level ie in German degrees hardness or CaCO3? You'll find the answer to this on your water/utility company website when you input your postcode.

It may be that your water doesn't suit the fish's requirements in terms of water hardness range. Up-to-date details of what each species requires can be found at https://www.fishkeeping.co.uk/modules/ ... resheets.php?cat=Tropical and www.seriouslyfish.com
shrimponablimp shrimponablimp
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  • Posted on: 26/8/2018 9:09
Re: Urgent help needed; nearly all fish dead and I have no idea why #3
Thanks for your reply, that link is really helpful. I looked up the hardness of my tap water and it's 20.7 mg/l.

Do you know why the tank water could be hard if the tap water isn't?

I also used the test strip I used in a glass of tap water, and the colour is somewhere in between 0 mg/l and 30 mg/l, which is in line with what you'd expect. I have been told the test strips are poor though so I'm going to get a liquid test kit, hopefully tomorrow.
Fishlady Fishlady
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  • Posted on: 26/8/2018 12:43
Re: Urgent help needed; nearly all fish dead and I have no idea why #4
20mg/L isn't hard, it's very soft which may explain the guppy death. Guppies are hard water fish where your others are best in soft water.

If the water in the tank is harder than your supply it usually means something in the tank is dissolving and releasing minerals into the water raising the hardness. Typical culprits are any limestone base rock, shells, and certain types of gravel.

Yor nitrate level being 0 is suspicious - usually, there is some nitrate in the tank as it's the final product of the cycle. Having none may mean there is no cycle happening, which in turn may mean there is ammonia in the water.
shrimponablimp shrimponablimp
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  • Posted on: 27/8/2018 20:38
Re: Urgent help needed; nearly all fish dead and I have no idea why #5
Thanks for your reply; I'm thinking of replacing the substrate. I looked into the gravel we bought when the tank was first set up, and we'd bought this:

http://www.petsathome.com/shop/en/pet ... pebbles-8kg?i=9&orderBy=3

I looked at the reviews and someone said that it was responsible for killing their fish and causing pH to rise in their tank. Any suggestions of safe alternatives?

Now I have the info about hard/soft water fish I'm going to factor that in when/if we restock.

Also, I used the liquid test kit I ordered yesterday, and it confirmed the results of the test strips. I think the low nitrates could be due to the fact that the tank is understocked, algae keeps blooming (I didn't mention it but it's a bit of a battle to keep the algae away, it comes back overnight). It just occurred to me when writing that the tank could actually have high nitrate levels but the algae bloom is masking it. So the nitrate levels might rise when I vac away the algae, kill/make the fish unhealthy, and then lower once the algae uses it up. Does that sound like a possible explanation? We have also have some nitrate minus we've used to try and kill the algae, but it's pretty ineffective. We use that occasionally, every few water changes.

So it could be that the nitrate is zero because not much is being produced, or that it's being diminished by the algae.