Corydoras wont stop dying

[seannx]

Sooo I'm really starting to get frustrated. I had 9 panda Cory's, 6 peppered corys, and 6 bronze corys. I'm left 5 bronze and 1 peppered Cory. Well I got 5 new peppered corys and now one of my bronze corys died. So peppered corys and 4 bronze at the moment.

They eat a very big range of foods, blood worms, veggies, flakes, egg, etc.

The water parameters are

Ammonia 0
Nitrite 0
Nitrate 10
Ph 7.6
Water hardness 7

They're all extremely active and healthy, as well as eating a ton. Until I just wake up and they're dead. There's no parasites or illness either.

It's a planted tank as well

Temp is 73

Gravel and rock for substrate

I really have no clue what is going on. And it's only the corydoras dying, literally all of my other fish are fine and I had my corys for about a year now and got them all pretty young.

Other tank mates, 1 kuhli loach, 2 rainbow sharks that don't touch the corys at all, 2 red bristlenose plecos that are still young and don't go near the corys unless eating but they eat algae wafers or stems, while the corys eat the smaller bits, and now I have 4 cherry barbs who are juveniles. As well as a bunch if baby snails. They've been dying way before the cherry barbs or snails came into the tank. Their bodies when dead have no marks on them either.

Have you checked TDS? A meter is only about $20 on Amazon. If the tap water is below 100, a product like Salty Shrimp can easily raise it to 150 TDS, and that will bring your PH down, too.
Definitely use Seachem Prime. Let the water sit in 5 gallon buckets at least 24 hours before.
I use this brand heater in each 5 gallon bucket. It has an easily adjustable temperature dial.

Hygger Mini Inline Quartz Glass Aquarium Heater with External Controller, Adjustable Submersible Betta Fish Tank Thermostat 50W​

Then get a digital food thermometer. They are cheap, and you can use it to check the water temperature in the tank and buckets. It will probably be a degree off, but will be consistent for the tank and buckets.
Once your water quality is worked out, consider two 50% monthly changes, and vacuum each time. Rinse the filter medium in the tank water and dose with Seachem Pristine.
I have 9 corydoras in a 32 gallon tank, with plenty of other community fish, and have never lost one or seen the behavior you describe.
Water usually stays between 77 and 78. On the occasional hot day it goes to 79.
Good luck!

 

[AdoraBelle Dearheart]

Corydoras cannot digest vegetable matter and if fed too much can suffer the consequences. They do not eat algae, which is a clue. They graze surfaces, including algae mats, looking for microscopic foods like crustaceans and insect larvae. I would not encourage veggie foods, i.e., don't put the zucchini etc in the tank, and if you need to feed plant-based foods for some fish don't do it more than once a week with cories present.

Cories and loaches should never be housed together in the same tank, so going forward, keep this in mind and decide which, but not both. A sand substrate will help the cories, and the loaches depending upon species.

There is no doubt at all but that the issue here was chlorine in the water, so that is now resolved. From all the data in this long thread, which I just read through again, there is no question otherwise.

Not disagreeing with any of this, but do want to add that the chlorine in the water was the main issue, but want to stress that it also had an effect on the nitrogen cycle. Both when adding chlorinated water to the tank killing BB, but also washing the filter in chlorinated, hot water, and throwing cartridges away. That these things also need to be resolved to stabilise the tank going forward, along with fixing the stocking and feeding problems.

@bianca_m35 There are ways to adapt your filter so that you never need to buy cartridges again! That cartridges-you-need-to-replace-monthly thing is basically a money making scheme by filter companies, and along with costing you a bomb, it's actually unhelpful to your tank. You're not alone in following their instructions - we see these problems here a lot and people listening to the filter instructions to replace the media, and throwing out most or all of the tank cycle in the process.

I really recommend these two videos to help you learn more about the nitrogen cycle (and why we only ever rinse filter media in old tank water, never untreated tapwater), and a useful video about how to modify your filter so it's doing as much as possible for your tank, while saving you a small fortune Both helped me a lot when I was new to the hobby and confused as heck!

 

[Avel1896]

Reminder :

Airstone raises pH as long as it is below 8.4 and OP is 7.8 tapwater and 7.6 tankwater.....
I think Cories do not need pH to be raised.

 

[IR_Crayoneater]

I keep my PH in my planted tank with Corys, Loaches, Fiddlers, Mollies and Platies at 7.6-7.8 and the temperature between 80-82. I believe you said your tank temperature was 73 ? Try raising that a little to, maybe a degree every 2 days, to maybe 78 . Every 2 water changes I dose with API quickstart, keep a 1/4 of a cuttlefish bone in one of the filters ( I run a Aquaclear 70 and 55 in my tank) and a small bag of crushed coral in the filter also that I change once a month. The cuttlefish bone isn't a necessity unless you have snails, crabs etc. although the calcium from them do benefit the fish. I also dose with aquarium salt ( I have a 55gal tank and put 1.5 tablespoons in once I hit 90% of the water changed, I put it into a 5 gallon bucket when I change the water), It will help with disease and stress, you just have to be careful with your dosage because corys and loaches cannot handle a lot of salinity.

As far as plants go, I have had pretty good luck with Hornwort, Amazon Swords, Red Ludwigia, Anacharis and just planted Monte Carlo for carpeting. I dose with Excel and Flourish every 3 days. I have 2 fairly large pieces of drift wood and one smaller branch ( that I have Anubias growing off of, you can tie it to driftwood and it will grow along it). The specific types are Malaysian driftwood, Spider wood and a Bonsai.

Large pieces of driftwood will lower the PH in your tank, the crushed coral raises it and increases hardness (my tap water is extremely soft). The driftwood also helps with their immune systems and parameters in your tank, besides giving them places to hide and feel secure. Just make sure you boil it in a large pot a few times to get rid of any bacteria or anything that came with them and some of the tannins or it will darken your water. ANYTHING, you put in your tank make sure you either boil it, Peroxide dip or quarantine.

I agree with others, Prime is a lifesaver when using tapwater and I would try rehoming the sharks. My corys and clown loaches live in relative piece with each other but I have always been advised not to add any type of shark or cichlid into my tank because of the types I have in there. I hope with the combined help of everyone in the forums, you can get your tank straightened out and relieve some stress off the fish and yourself lol As always, this forum has the most amazing people on it.

 

[AdoraBelle Dearheart]

Reminder :

Airstone raises pH as long as it is below 8.4 and OP is 7.8 tapwater and 7.6 tankwater.....
I think Cories do not need pH to be raised.

I definitely wasn't aware of this, so thank you

<<< Chemistry dunce

@Essjay Sorry to call on you again to help me understand simple concepts, but any chance you can explain in layman's terms how the oxygenation changes the pH please? I know that increased temperature in water reduces the amount of oxygen it can hold and why, but admit I still struggle with pH, and it's interaction with GH and KH - and now an airstone?

Also, I assume the same principle applies with a sponge filter?

 

[Essjay]

Airstones increase gas exchange at the water surface. Oxygen is used by fish so oxygen dissolves in the water to replace that which is used. Carbon dioxide is breathed out by fish so carbon dioxide gasses out of the water at the surface. Carbon dioxide dissolves in water to form the weak acid carbonic acid, and acids lower pH. If carbon dioxide leaves the water, there is less acid so the pH rises.

All filters have the same effect if they cause turbulence at the water surface.

 

[Avel1896]

I definitely wasn't aware of this, so thank you

You're welcome
Simply put. As you raise water swirl you make CO2 (that participate to decrease pH) vanishing. Less CO2 = more O2.

 

[bianca_m35]

I have multiple corys and find that they are some of the hardiest fish when it comes to water chemistry. I have gone 2 weeks without feeding them and they have also been fine. That being said I think we need to look elsewhere beside water chemistry.

you said they are on pebble/rock substrate. Ik they prefer sand but they can be fine on rock. Are the pebbles small enough that they can eat them but not digest them/ pass them through. This could cause impaction which is fatal.

Yes they can pass It through!

 

[bianca_m35]

Corydoras cannot digest vegetable matter and if fed too much can suffer the consequences. They do not eat algae, which is a clue. They graze surfaces, including algae mats, looking for microscopic foods like crustaceans and insect larvae. I would not encourage veggie foods, i.e., don't put the zucchini etc in the tank, and if you need to feed plant-based foods for some fish don't do it more than once a week with cories present.

Cories and loaches should never be housed together in the same tank, so going forward, keep this in mind and decide which, but not both. A sand substrate will help the cories, and the loaches depending upon species.

There is no doubt at all but that the issue here was chlorine in the water, so that is now resolved. From all the data in this long thread, which I just read through again, there is no question otherwise.

I only have the cories, the Sharks and plecos now which I will remove a BN and the Sharks.

 

[bianca_m35]

I only have the cories, the Sharks and plecos now which I will remove a BN and the Sharks.

Also I don't feed veggies much, about once a month and the plecos are the ones that eat them! The corys don't typically eat the veggies I put in there. They eat a pellet and flake diet will sometimes eat a tiny bit of veggies but not much.

 

[bianca_m35]

Not disagreeing with any of this, but do want to add that the chlorine in the water was the main issue, but want to stress that it also had an effect on the nitrogen cycle. Both when adding chlorinated water to the tank killing BB, but also washing the filter in chlorinated, hot water, and throwing cartridges away. That these things also need to be resolved to stabilise the tank going forward, along with fixing the stocking and feeding problems.

@bianca_m35 There are ways to adapt your filter so that you never need to buy cartridges again! That cartridges-you-need-to-replace-monthly thing is basically a money making scheme by filter companies, and along with costing you a bomb, it's actually unhelpful to your tank. You're not alone in following their instructions - we see these problems here a lot and people listening to the filter instructions to replace the media, and throwing out most or all of the tank cycle in the process.

I really recommend these two videos to help you learn more about the nitrogen cycle (and why we only ever rinse filter media in old tank water, never untreated tapwater), and a useful video about how to modify your filter so it's doing as much as possible for your tank, while saving you a small fortune Both helped me a lot when I was new to the hobby and confused as heck!

The cartridge I have at the moment hasn't been changed in 3 months though. The ones before I replaced monthly. I ran out of cartridges 3 months ago and just never got a new one lol. I wanted to get a sponge filter actually but never ended up getting one. I had no idea it was a scam I just though it caused bad bacteria growth but now that you mention it when I was replacing them monthly I had a ton of unwanted algae and little ammonia spikes all the time. I will watch the videos!!

Also I did a water test and it's

.25 ammonia
0 nitrite
10 nitrate

At least it drastically went down. And the fish seem much happier at the moment.

 

[Slaphppy7]

The cartridge I have at the moment hasn't been changed in 3 months though. The ones before I replaced monthly. I ran out of cartridges 3 months ago and just never got a new one lol. I wanted to get a sponge filter actually but never ended up getting one. I had no idea it was a scam I just though it caused bad bacteria growth but now that you mention it when I was replacing them monthly I had a ton of unwanted algae and little ammonia spikes all the time. I will watch the videos!!

Also I did a water test and it's

.25 ammonia
0 nitrite
10 nitrate

At least it drastically went down. And the fish seem much happier at the moment.

Time for another WC

 

[AdoraBelle Dearheart]

Also I did a water test and it's

.25 ammonia
0 nitrite
10 nitrate

Good that you're keeping on top of testing!

Time for another WC

This! ^^^
Anytime ammonia or nitrites are anything other than zero, a W/C is needed ASAP.
Remember that even if it's "only" 0.25ppm now, it's likely rising... and we don't even want 0.25ppm ammonia in there. W/C 50-75% time!

 

[bianca_m35]

Good that you're keeping on top of testing!

This! ^^^
Anytime ammonia or nitrites are anything other than zero, a W/C is needed ASAP.
Remember that even if it's "only" 0.25ppm now, it's likely rising... and we don't even want 0.25ppm ammonia in there. W/C 50-75% time!

Sorry lol I just meant I'm glad it's not 2.0 this time cause I freaked out last time. Why is this ammonia not stopping omg

 

[Slaphppy7]

It will eventually stop showing up on the test...patience is key in this hobby...nothing good ever happens fast, I have found.