Fish tank disaster

[VenusClapTrap]

Any aquarium experts on here?

We got back last night after three days away. A local teenager was looking after our animals and fish. She sent me a message yesterday morning, obviously a bit upset, because ‘one or two’ fish were floating belly up and the water had a ‘musty smell’. I told her not to worry, sometimes fish die and it’s just life.

We got home to what I can only describe as fish soup. The water was opaque and stank of rotting fish. We had about twenty fish and some shrimp, and the surface of the water was full of rotting bodies in various states of decay. It was horrific. DS(12) was inconsolable.

We all mucked in and were up till after 11pm sorting it out. We removed the dead fish and about a third of the water, cleaned the scum clinging the sides, cleaned out the filter, and tried to clear out as much of the rotting food as possible. There was food all over the gravel at the bottom; she’d clearly been massively over feeding them.

We then filled it back up with fresh water and left it overnight to settle.

The only survivors are two plecos and one baby guppy. It’s amazing anything survived really.

This morning I was hoping the water might have cleared, but it’s still really cloudy and smelly.

My question is can I take out more water today? I’m worried about replacing too much and harming the survivors. How long should I leave it before another clean out? Any advice appreciated - I know there’ll be knowledgable people on here.

How the hell did that happen in 3 days ! Did die turn the filter off maybe a power cut ?

the plecs are very resilient and will help clean the tank well. I wouldn’t change anymore water just make sure you keep the filters cleaned and get some air bubbling in there. Tbh the damage is done to the fish except for one vert strong guppy ! So it’s just stabilising the water and plants which will take a while. Don’t add anymore fish until the water tests are clear again.

I know, I can’t believe how fast it went from healthy tank to Armageddon. I wondered about a power cut; it’s possible. I don’t think the filter had been turned off; the socket is hard to reach so unlikely to have happened by accident and it was definitely on when we got home - first thing I checked.

Thanks for the advice. We’ll leave it alone now until it’s back to normal.

We had exactly this happen to our fish when left a local teenager in charge. I think she massively overfed them, most died including our previously prolific Molly breeder fish so the tank was never the same again.

Sorry that was not a very helpful response OP, just bringing back bad memories.
I hope you're able to get the tank to settle and can then introduce some new fish again

In a well established tank even the filter dying for a few days wouldn’t lead to that.

Most likely over fed by a lot. We had a situation once many years ago when my oldest was a toddler. Dumped a whole 2kg tub of fish food into our 4 tank. Thankfully seen. Spend all day emptying cleaning and refilling that tank it definitely had a pong for a couple of days still but we luckily only lost a couple fish. It was a heavily planted tank so when I say all day my livingroom was like a wet room full of buckets and tarps and we shut the filter off straight away so the the bad water hadn’t really got chance to do too much damage in there.

Sorry to hear this - how awful. If you are in the UK and have a Maidenhead Aquatics nearby I'd pop in or give them a call - I always find them knowledgeable and helpful. Or try YouTube.

This is why I always leave spoons with the first days feed for my cat sitter and make it very clear if they aren't sure less rather than more. It's most people who love animals instinct to be generous with food and to be kind and feed extra if they look hungry.

I'm sorry about your lost fishes.

I’m so sorry this happened to you too.

I would completely clear the tank and give it a good scrub and start again. The bacteria and fungus will still be in the structures, filter and substrate. Keep the remaining fish in a small holding tank for now and thoroughly sanitise everything else. Get new substrate etc. The teenager must be really dim to have trashed a fishtank in three days. It's obvious fish don't need lots of food because they're only small.

Is it a biorb? I was looking after a friends and their bubble machine had broken (no idea how long for) so the filter wasn’t working. Luckily I clocked it before more than one died.

id guess the teenager had been over feeding, but even that for three days would be impressive.

Assuming you showed the teen exactly how much to feed, and there was THAT much in the tank, I'd be furious.

But also some sympathy with the urge to overfeed. I recently looked after someone's fishtank and followed their instructions exactly, but definitely thought it looked like a really tiny amount of food. It's not that obvious if you aren't used to fish, and in comparison with other pets, it is miniscule portions.

I probably erred on the side of underfeeding, knowing it would be okay for a few days and also understanding the impact on water quality, but a teen might not think that through

Fill any couple of buckets of water and leave them for the chlorine to evaporate out. You don't want to use fresh tap water, but if it's left for a couple of days, you'll get away with it.

I had an RO unit to produce 'tank ready' water in my tropical tank, and it was excellent.

Sounds like a tub of food was dumped in to me, as PP have said.

If you've done a water change and a gravel clean already, I wouldn't do it again. Change/clean your filter medium, and angle the outlet so it disturbs the water to oxygenate. If you have live plants in there they'll help massively. You can dose up on your aquarium bacteria as if you are starting a new tank to help the break down a bit more. Another partial water change in a week and reassess from there. You may need to do partial water changes and double up on the cycling liquid for a few weeks until it stabilises again. If you are only away for a short period of time like 3 days, I wouldn't bother having anyone in to feed them to avoid this happening again. Or you can get slow release feeding tablets that you can fish out when you return if you are longer. Good luck

I’ve done this myself, I think it all started with one or two dead ones which then polluted the rest of the water because they’d died overnight and we hadn’t been able to get them out in time. Then the rest of them died pretty quickly. So it may have been a combination of overfeeding and then a couple of dead ones.
I won’t comment on what to do next, as I’m clearly also shit with fish.

It’s horrible though.

You can exchange up to a 3rd of the water every 24 hours. It's not just about the nitrogen cycle and the bacteria - it's also to lower the risk of shock of rapidly changing ph or water mineral levels on the fish.

Keep changing 1/3 of the water every day until your water tests are normal (if you do not test water as a routine now, get a test kit asap so you can track) and the tank looks clear again, indicating your good bacteria have rebuilt their colonies such that they can now handle the nitrogen being produced by rotting food and live fish.

You can get gravitational powered gravel cleaners for cheap enough that 'suck' the food particles out of the gravel without picking up the gravel. If you don't have one, they can normally found at any fish store and are not expensive. Might be worth getting one to give the gravel a 'vacuum'.

I've also found Seachem Prime to be very useful in scenerios like this to help detoxify the nitrogen in the water to help in an emergency.

Thanks everyone. I do think this could have been a result of a missed dead fish in addition to over feeding, causing things to spiral rapidly. Some of the fish didn’t look like they’d been dead long at all, but there was also a load of gungy rotten soupy remains.

I can’t find it in me to be too angry with the teen. She’s looked after all the animals on a number of occasions, and there’s never been a problem before, although she does tend to overfeed the cats and guinea pigs a bit (they’re not complaining though!). She’s an animal lover and this will have upset her a lot.

Dd and I spent some time this evening sieving out more gunge that had collected on the surface. I can’t move the surviving fish into another tank because I don’t have one, much as I’d like to do a deep clean. But, the baby guppy was swimming around very perkily chasing the net, so we had to be very careful not to scoop it up. The plecs are doing their thing, hopefully feasting, and I’ve ordered a water testing kit.

The whole house smells of rotten fish.

Do you not had even a washing up bowl you could get those raining to safety so you can clean.