All the fish are dying and we don't know why, please help?

[MumofBoys79]

So we recently got a 50L tropical fish tank. It took about a month or so for the nitrite (etc) levels to settle down. However, during this time we managed to sustain our three first fish, a guppy, molly and bronze corydora. In fact, the molly randomly had babies, most disappeared but one lasted quite a while, before it also disappeared. The levels settled down and all three fish seemed to be doing well, until the lovely guppy died - possibly a growth. Next the black molly developed white spot which we treated and got rid of.

Then we got a dwarf gourami and five cardinal tetra. A short while later, the tetra all died (neon tetra disease we think). Now the molly has also died - it didn't look well for a while. The gourami also looks unwell.

The bronze corydora is the only one that seems to be okay.

Is this bad luck? We're tempted to not got any more fish, give up and sell the tank. We check the levels, temp, etc. They all seem okay, but it's been one thing after another. It's really sad and not a great first pet experience for the kids. It's also expensive to keep buying things to try to deal with each issue.

Any advice please? Any help will be much gratefully received. Thanks in advance x

Fairly new to fishkeeping here too but the advice I’ve had suggests that your tank may be too small - I’ve been told anything under 100l probably only really suitable for a single Betta. Sympathy as it is pretty miserable watching them die and not knowing what you’re doing wrong x

I'm absolutely not an expert but posting before someone else comes along to keep the thread bumped. We gave up keeping goldfish as it was just too much work and they were disgusting tbh!

Some things to consider:

That sounds like an awful lot of fish for a 50L tank, have you checked with an online stocking calculator?

How are you checking the ammonia, nitrite etc levels? If memory serves you need a proper little kit with test tubes etc not just test strips.

The tank may not have cycled fully yet.

What are you treating the water with before adding to the tank?

I would do an entire water change and clean everything in thecrank before you out the fish back i .Get some oxygenating real life tank plants. Are you adding the proper solution to the water to counteract the fact that it is tap water. Are you regularly cleaning the filter in your pump? Make sure you're not overfeeding.

That does sound like quite a few fish for a tank that size. How often and what percentage water changes are you doing?

Also you need hardier fish, guppies die easily I think!

Also you need hardier fish, guppies die easily I think!

Guppies are usually practically indestructible.

We were getting a lot of deaths in the first few months we had our tank. We thought we were doing everything by the book but it turns out it was because we were fully cleaning the filters in tap water. We live in a very hard water area so some of the levels were very high. We now buy special water from the aquarium place near us for the week water change.

What exactly are the water parameters, especially ammonia, nitrite and nitrates? Are you using a liquid kit to test? The strips are notoriously inaccurate.

What is your tank cleaning routine? What kind of filter do you have? What was your cycling process before you got fish? Or did you do a fish-in cycle with the guppies etc?

A 50L is considered pretty small, borderline a nano tank, for most livebearers and shoaling fish I would recommend an absolute minimum of 100L really. Fish like Corydoras also need to be in groups, minimum 3-4 but ideally more than 6.

I just wanted to thank everyone for their advice, I really appreciate it.

We have been using liquid test kits, all seems fine in that respect. Changing 50% of the water every two weeks roughly.

Anyway, the cardinal tetras and eventually the dwarf gourami died, sadly. My instinct tells me the cardinal tetra brought neon tetra disease with them.

We were left with one small corydora, who seems fine! We've added another corydora. They seem to be enjoying each other.

Given it is a 50L tank, I'm going to keep the fish numbers low as advised above.

So will probably get another two fish (not bottom feeders). Need two more hardy fish to keep. If anyone has any suggestions let me know!

Thanks for all your help everyone, much appreciated.

Actually we will get one more corydora (we currently have a bronze and black fin), and something else?

It’s better to have Corys of the same species rather than a mix and match.

Thanks for all your advice bunny geek.

I think changing less of the water more frequently might help. You could always do a shrimp tank?