Cory Losses

[max1zzz]

After not having lost any Cory's for a long time (5ish years) I seem to be slowly loosing corys out of my 240L tank, so far i have lost about 5 in the last 6 months or so
Most of the ones I have lost seem to have been the larger adult ones, and all showed no sign of illness that I could see with the exception of one that looked fairly poorly for a few days before it died (which also happened to be the one younger one I lost) I was particularly sad to find my female sterbai dead while I was doing my weekly water change on saturday, She had been breeding successfully up to just a few weeks ago (And she was good at hiding the eggs, I never saw a single one of them )

I can't find anything obviously wrong, Ammonia and Nitrite levels are at 0, Nitrates are low (I lost the original test card that came with the API kit so it's hard to give a exact number but the colour change is minimal)
There are no agressive fish in the tank (2x female BN, A assortment of corys (I am unsure of exact numbers as I have lost a few but also have several batches of fry, probably around the 15 mark made up of Bronzes, Sterbai, a single Trilinertrus, and 3x Gold Lazer), 11 Glass Cat's and 3 teras (1 cardinal and 2x rummynose) the tank has lots of filtration (2x Eheim Pro 4+ 600) I don't inject C02 as my previous attempts ended up causing a filer crash. I have been adding plant fertiliser recently (APF's recommended starting dose for EI ferts) however I only started doing this in the last couple of months as I had to change tanks due to the old one springing a leak so I took the opportunity to replant the tank, all the cory deaths except my female sterbai happened in the old tank before I started doing this

One Thing I can think of that could maybe be causing a issue is that I have been adding the water conditioner to the tank and then topping it up with the hose when doing water changes, although the bottle says this is OK i'm not 100% sure now

[Gingerlove05]

What is your water hardness? Corys are a soft water species so will generally do better in soft water.
Have you been turning the filters off when adding water before adding the dechlorinator or vice-versa?

[max1zzz]

Probably a little on the hard side, about 7dgh IIRC,I do have RO water for my marine tank though so i could mix some of that in to soften it up a little

Any I have just been adding the dechlorinator, then adding tap water with the filters still turned on.... Which now you mention it is probably not the best thing to be doing! I am going to be going back to pre-mixing the water and dechlorinator, just waiting for the 2x25L water bottles I ordered off ebay to arrive

[Stephen]

I have just been adding the dechlorinator, then adding tap water with the filters still turned on....

How are you adding dechlorinator?
Straight in to the tank or in to buckets of clean water and then in to the tank.
How much dechlorinator? Enough for the amount of clean water or for the whole tank volume?

What is the usual tank water temperature?

Thanks

[max1zzz]

Straight into the tank, approx 10ml of prime which should be good for 400l of water

temp is approx 24C

[plankton]

Sorry for your losses.
It does sound as though keeping the filters on during the water change has possibly reduced the number of munchers in the filter from the unconditioned tapwater going through.
This will have (probably) caused ammonia spikes, and corys don't cope with ammonia at all.

[Stephen]

I use a hose when re-filling my aquarium and add Prime to where the water is coming in to the aquarium.
As soon as the tap is turned on I start dosing Prime, not all at once but gradually as the water level gets higher.
On my 550L aquarium the dosage is approx 15ml of Prime (I use closer to 20ml) and add about 5ml at the start at the point where the water is entering the aquarium.
As the water level rises I add another 5ml (approx) and so on, the dosage is complete when the water level is approx 75% full.
I never dose Prime after the water change, but during the water change.
I also make sure that the clean water entering the aquarium is approx the same temperature as the water in the aquarium (24.5C) maybe a degree lower but close enough.
Usually I switch off my filters during the water change to protect the beneficial bacteria.
Yesterday I only switched off the filter closest to where the clean water is entering the aquarium, I have two filters.
The reason I left one filter running was because it was so hot yesterday and I wanted to keep the aquarium well oxygenated, usually both are switched off.

How are you feeding your cory and with what?
Cory require a high protein diet, I use JMC high protein mini granules (yellow label, white top) most days and bloodworm on other days with occasional Hikari sinking wafers (not algae wafers). A good varied diet but my main food for cory is the JMC high protein mini granules. The cory will also nibble on other foods which are designated for other fish.

All the best

[plankton]

@Stephen remember you won't be able to get the JMC food for much longer as they've gone out of business.
Have a look at Heron's Pet Foods, I'm using those now after a recommendation from @Martinspuddle ......

[Stephen]

@Stephen remember you won't be able to get the JMC food for much longer as they've gone out of business.
Have a look at Heron's Pet Foods, I'm using those now after a recommendation from @Martinspuddle ......

Thanks Ian, I have plenty of stock at the moment and still can get it on-line in places.
@plankton What is this Heron's Pet Foods? How are the cory liking it?

Thanks

[max1zzz]

Thanks guys,
I have been adding the full dose of prime (well slightly more, the full dose is 6-7ml iirc but I have been using 10ml as it's easier to measure out) just before i start adding water from the hose. I don't know why it never occurred to me to turn the darn filters off before adding the water, If I continue using the hose I will be doing this however I think I am going to go back to pre mixing the water and prime which will also give me a chance to temperature match the water (Something I have not been doing for quite a while now)

In regards to food I have mainly been feeding Vitalis Catfish Pellets which the corys seem to love (it's 40.3% protein according to the pot) for the last couple of months, I usually feed the aforementioned pellet and frozen food on a two day rotation (or dry, frozen and live on a 3 day rotation if i am being really organised) but I was running low on frozen just before the lockdown and haven't had a chance to restock (I would usually feed bloodworm and / or brine shrimp as the frozen ones). I'll have a look and see if I can get the JMC pellet's online otherwise I'll look at the Heron's Pet Foods ones

Do you guys think it is worth softening the water in the tank?