I hope someone can help with my question.
I used to keep tropical fish around 10 years ago, I had guppies, plecos, a siamese figher and neon tetra. It was a pretty cool aquarium but I gave it up when I moved house with my parents.
In April I got myself a new 80 litre aquarium with a built in filter, a photo of the tank is attached. The light doesn't work and I had to buy a heater but apart from that it's perfectly fine.
To bed the tank in I bought 2 gourami,2 mollies and 2 nano shrimp around the middle of May. The tank had been running for around a month and I had water tests done at my local pets at home store- nothing was wrong and they were happy for me to go ahead and start the tank off.
Things seemed to be going fine so after a while I bought 4 Neon Tetra, 1 Siamese Fighter, 2 more nano shrimp and a pleco.
The pleco died about 3 days after I bought him, put it down to stress and was offered a replacement as they tested the water again and nothing was wrong. I bought 4 more neon tetra and a further pleco to keep the replacement company, all plecos have been about 6cm long when I bought them.
A neon died last week however I thought this was due to stress again and wrote it off.
I've come home from work today to find both plecos dead, all but one Neon (6) dead and one molly dead.
I've done an instant water change in case it was due to anything in the water so I may prolong those which are left. There's a few bit of flakes left at the bottom as a result of changing fish food (I've changed from an expensive brand to Aldi Fish Flakes and they don't seem as keen on this!).
I know that excess food can result in ammonia spiking, however surely it would take a lot to kill so many in such a large tank?
I'm going to pets at home tomorrow with the dead fish and a water sample in a separate container (to prevent overnight nitrate spikes in the water bottle due to the dead bodies) to see what they suggest, however I know that they may not know everything.
I'm distraught and wonder if anyone here has ever faced something like this and if they can suggest anything for me?