Corey catfish both died?

[Tomie]

Hello, about a week ago I purchased two small Corey catfish. They have been happy little fish, they stayed together and happily swam around the bottom of my tank. Last night they both looked happy and healthy. I’ve woke up this morning and one of them is stuck in a bush at the bottom of my tank and the other is sucked to the filter. I have no fish that are agressive, they are all green community fish. I do have a brittle nose pleco, which I have seen ‘pounce’ a few times but both fish always seem quick enough to hurry away. Any suggestions as to why this could of happened? I’m gutted as I’m just so puzzled how both of them have died at the same time. I’ve done a water test there’s no ammonia in the tank.

 

[Colin_T]

How long has the tank been set up for?

What is the nitrite, nitrate & pH of the tank water?

What did you do to the tank yesterday?

When was the last time you did a water change and gravel clean on the tank, and how much water did you change?

Do you dechlorinate the water before adding it to the tank?

What else is in the tank besides a bristlenose?

What did the Corydoras look like when they died, eg: did they have any green, red, white patches on them?
Do you have a photo of the dead fish?

Can you post a picture of the other fishes in the tank? They might have something that killed the cories.

 

[Tomie]

Hello. Thanks for your reply and I apologise for how long its taken to give a reply.

My tank has been running for 3 month and i've had no problem what-so-ever since upgrading to my 120 litre tank, none of my fish have died and they all seem settled. About a week ago myself and my partner took a trip into town and bought 4 new plants, we already have quite a few added to the tank but these plants caught my eye especially with them being pink and red, once home I planted them right away. It was the next morning when I woke up to go to work I noticed my two corey catfish (which i'd only had a week) looked to be dead. Both cories looked as they did when they was alive, nothing looked unordinary. Since this happened we thought it could be the 4 new plants so we took them out right away and haven't put them back in. I also noticed that the water looked a tad cloudy, the evening before I was working late and asked my partner to do a water change (it's usually me who does this) and after doing nothing but going over everything wondering how this could of happened my partner said they could of put too much water conditioner/dechlorinator into the buckets of water, but we googled this and it said water conditioner can't really kill a fish? Is this true? Since this has happened I've done 3 fairly big water changes and non of my fish seem to be poorly. Its just worrying and puzzling how both fish would die at the same time. Also, around same day my two fish died, I woke up not only to find the fish but my huge plant which took over the tank had all been shredded. Most the leaves on the plant just came off, over night! It looked as though somebody had hacked away at it with a hedge trimmer! Bits are still coming away from it, before this nothing ever came from the plant.

And to answer your question about the gravel clean, we do a gravel clean almost every time we do a water change.

Sorry for the novel lol! Didn't want to miss anything out.

Ammonia - 0
Nitrate - 0
Nitrite - 0
ph - .6.2

 

[Colin_T]

So you got some new plants and a couple of Corydoras about a week ago. The water went cloudy when you added the plants so your partner did a water change. The following day the 2 new cories were dead with no signs of damage or illness.

Did your partner use a fish only bucket for the water change?

You can double and triple dose dechlorinators without any issue. In fact most require a double dose when treating chloramine.

The new cories possibly had an issue when you bought them and the stress of the water change pushed them over the edge.

As a general rule, pink and red plants are not true aquatic plants and don't usually do well underwater. If you can post a picture of them and the other plant that is falling apart we might be able to offer more info on them.

 

[HakimChef]

I own a 30-gallon tank, with a large bristle nose pleco and five cories as well as some other peaceful fish. I find that the key to keeping the pleco from bullying is to give him some driftwood and lots of territory. As Colin said, the cories may have been very stressed from the change to a new aquarium and the extra stress of a water change was just too much for them. From my experience with albino cories, you should feed them bloodworms in the middle of the day and stay a bit far from the tank for the first week. This helped my two new baby cories settle in, seeing as whenever I came near the tank glass to watch they'd run and hide seeming stressed. Now, a week later they're active and not shy anymore. I'd say that once you get new fish don't change the water for two weeks. So you can let them acclimate to the tank.