Gradually losing my pygmy corydoras

[Bradders]

Edit - this resource seems good - 3.3.1. Amount in Depth

Yes, I used this as a starting base for my fish.
Although mine are all adults, I feed about 0.75% to 1% of body weight. (I lean on the side of less than more). I did weigh out 2% once and had a heart attack at the amount of food! So I just observed and ensured all fed fine on the food + algae and growing.

 

[dw1305]

Hi all,

Aside to @dw1305 , would you mind sharing your water parameters please?

Soft water, mainly because I use rainwater. Our rainwater has some <"carbonate buffering"> (from limestone dust).

I don't measure any parameters now regularly just use the <"Snail shell and Duckweed Indices">. I used to measure conductivity and aim to remain in <"between 80 - 150 microS">.

Our tap water is very consistent (<"about 17 dGH : 17 dKH">), but the rainwater is softer ("has lower conductivity") in the winter.

cheers Darrel

 

[Katharine]

Hi all,

Soft water, mainly because I use rainwater. Our rainwater has some <"carbonate buffering"> (from limestone dust).

I don't measure any parameters now regularly just use the <"Snail shell and Duckweed Indices">. I used to measure conductivity and aim to remain in <"between 80 - 150 microS">.

Our tap water is very consistent (<"about 17 dGH : 17 dKH">), but the rainwater is softer ("has lower conductivity") in the winter.

cheers Darrel

Corydoras pygmaeus – Pygmy Cory — Seriously Fish suggests the following:

Water Conditions
Temperature: 72 to 79°F (22 to 26°C)
pH: 6.4 to 7.4
Hardness: 2 to 15°H but preferably below 8.

Which suggests I'm at the upper end of the acceptable pH range, but hopefully not sufficient to cause this level of problems. I would drop the water hardness further but that would likely be bad for the snails.

To update - none of the remaining corys have looked sick in the last few days, though I am still worrying and it's definitely early days.

 

[Bradders]

To update - none of the remaining corys have looked sick in the last few days, though I am still worrying and it's definitely early days.

Well, that is great news! At least it is not getting steadily worse.

 

[Katharine]

Well, that is great news! At least it is not getting steadily worse.

🤞 🤞 🤞

 

[hypnogogia]

I don't measure any parameters now regularly just use the <"Snail shell and Duckweed Indices">. I used to measure conductivity and aim to remain in <"between 80 - 150 microS">.

Interesting. What dGH and dKH do you estimate that you have, given the low conductivity?

 

[dw1305]

Hi all,

Interesting. What dGH and dKH do you estimate that you have, given the low conductivity?

<"Three or four for both">? The dGH might be a little bit higher, just because I add a smidge of Epsom Salts (MgSO4.7H2O).

Cheers Darrel

 

[MichaelJ]

Interesting. What dGH and dKH do you estimate that you have, given the low conductivity?

Hi all,

Three or four for both? The dGH might be a little bit higher, just because I add a smidge of Epsom Salts (MgSO4.7H2O).

Cheers Darrel

Thats nice Darrel... I figure the 3-4 dGH/dKH ( from limestone / Calcium Carbonate I assume with your tap being 17 dGH/dKH), would put you in the 55-70 uS/cm range. The addition of MgSO4 will add to that. But that should still leave plenty of headroom for fertilizers mainly a little bit of NPK, if your upper limit target is 150 uS/cm.

Cheers,
Michael

 

[Calamardo Tentaculos]

Corydoras pygmaeus – Pygmy Cory — Seriously Fish suggests the following:

Water Conditions
Temperature: 72 to 79°F (22 to 26°C)
pH: 6.4 to 7.4
Hardness: 2 to 15°H but preferably below 8.

Which suggests I'm at the upper end of the acceptable pH range, but hopefully not sufficient to cause this level of problems. I would drop the water hardness further but that would likely be bad for the snails.

To update - none of the remaining corys have looked sick in the last few days, though I am still worrying and it's definitely early days.

That's great! Hopefully the rest will be fine!

I just had a chat with the folks at Fish Planet London and they said that they use tap water for all their fish. However, their tap water has a PH of 7.2 so it's within the range given by Seriously Fish.

I wonder whether lowering the PH might make the difference...

 

[MichaelJ]

Corydoras pygmaeus – Pygmy Cory — Seriously Fish suggests the following:

Water Conditions
Temperature: 72 to 79°F (22 to 26°C)
pH: 6.4 to 7.4
Hardness: 2 to 15°H but preferably below 8.

Which suggests I'm at the upper end of the acceptable pH range, but hopefully not sufficient to cause this level of problems. I would drop the water hardness further but that would likely be bad for the snails.

To update - none of the remaining corys have looked sick in the last few days, though I am still worrying and it's definitely early days.

The quoted water parameters, unless they are very off the rails wont hurt your Cory's - and yours are definitely not off the rails. Rapid change in water parameters is more likely to be harmful... for instance if the water they came from varies wildly from the water in your tank etc. or if you make large changes to your water parameters over a short duration of time. Tweaking dGH a couple of degrees or your pH at the fractional level wont have any short term effect if your Cory's are already sick, but you may want to do so otherwise as it is generally beneficial for soft water fish and plants alike. Btw. your snail will be just fine if you drop the dGH a couple of degrees - I am not aware of any snails that can't thrive in waters with a dGH around 5-6.

Cheers,
Michael

 

[dw1305]

Hi all,

would put you in the 55-70 uS/cm range. The addition of MgSO4 will add to that. But that should still leave plenty of headroom for fertilizers mainly a little bit of NPK, if your upper limit target is 150 uS/cm.

Nice and I'd like to say that that conductivity level was based on your logical thought process, but it wasn't, it was just that they are approximately the top and bottom of the <"variability of the rainwater">.

All I need to do then is find organisms (plants, fish, invertebrates) that are happy in that water. It is the <"path of least resistance">, and precludes from keeping <"true blackwater fish"> (not soft enough and too alkaline) or <"speciality" snails"> (too soft and not alkaline enough).

from limestone / Calcium Carbonate I assume with your tap being 17 dGH/dKH

Yes, all the hardness and alkalinity from a <"Jurassic age limestone aquifer">. These figures are from 2019, but you can see that it doesn't vary very much.

These are the current figures from Wessex Water for "Zone 41 Fiveways", calcium carbonate = 328 mg/L, NO3 = 8 mg/L and conductivity 630 microS.

You can convert the 328 mg/L CaCO3 value to dKH using: 1dKH = 17.86 mg/L CaCO3 (it is the same value for dGH, the derivations are at <"Water Hardness"> ) 328/17.86 = 18.3 dKH.

This was today's offering.

This is what happens when this aquifer water reaches ground level, <"warms and loses some dissolved CO2">.

cheers Darrel

 

[dw1305]

Hi all,

I just had a chat with the folks at Fish Planet London and they said that they use tap water for all their fish. However, their tap water has a PH of 7.2 so it's within the range given by Seriously Fish.

I'd be really surprised if that was the real pH of their tap water. I think all of N. London will get hard, alkaline water with a pH near pH 8. The water map is here <"Some handy facts about water">.

I wonder whether lowering the PH might make the difference...

It might, but not if you <"lower the pH"> with <"pH buffers"> etc.

The only way to get softer water is either RO or rain. You can lower the alkalinity (dKH) by adding acid (the bicarbonate HCO3- ions are converted to CO2), but you will still have the calcium (Ca+) ions etc. You can remove the calcium ions by ion exchange and swapping each Ca++ ion for two sodium (Na+) but then you <"have even less suitable water">, if that makes sense? I'll add in @MichaelJ .

That is why I like conductivity as a measure, it <"cuts straight to the chase">, pH values always need some interpretation.

cheers Darrel

 

[Conort2]

That's great! Hopefully the rest will be fine!

I just had a chat with the folks at Fish Planet London and they said that they use tap water for all their fish. However, their tap water has a PH of 7.2 so it's within the range given by Seriously Fish.

I wonder whether lowering the PH might make the difference...

I wouldn’t start messing about with your PH, it’ll cause more issues. You need to keep things stable.

I don’t think your water is the problem.

 

[dw1305]

Hi all,

I wouldn’t start messing about with your PH, it’ll cause more issues. You need to keep things stable.

I don’t think your water is the problem.

I agree with at @Conort2, I don't think your water is the problem.

Personally if I didn't have access to rainwater I'd <"use our tap water">, and keep plants, fish and snails that <"need / enjoy hard, alkaline water">.

If you like, it is <"horses for courses">.

Cheers Darrel

 

[fredi]

Hi all,

I'd be really surprised if that was the real pH of their tap water. I think all of N. London will get hard, alkaline water with a pH near pH 8. The water map is here <"Some handy facts about water">.

It might, but not if you <"lower the pH"> with <"pH buffers"> etc.

The only way to get softer water is either RO or rain. You can lower the alkalinity (dKH) by adding acid (the bicarbonate HCO3- ions are converted to CO2), but you will still have the calcium (Ca+) ions etc. You can remove the calcium ions by ion exchange and swapping each Ca++ ion for two sodium (Na+) but then you <"have even less suitable water">, if that makes sense? I'll add in @MichaelJ .

That is why I like conductivity as a measure, it <"cuts straight to the chase">, pH values always need some interpretation.

cheers Darrel

I have purchased quite a few “soft water” fish from wholesale tropicals, who definitely use “London tapwater”, which I have found to be hard and nearer 8 than 7 in pH, never had a problem with anything purchased here, I do slowly acclimatise the fish to my water parameters

 

[dw1305]

Hi all,

I have purchased quite a few “soft water” fish from wholesale tropicals, who definitely use “London tapwater”, never had a problem with anything purchased here, I do slowly acclimatise the fish to my water parameters

Away from fish <"like Parosphromenus spp">, maintenance is often fine in the "wrong water" if <"other factors are good">.

Because I'm both <"incredibly lazy and tight with my money"> I like to keep fish that produce at least a trickle of fry (with minimum intervention) and usually soft water fish don't breed successfully in harder water.

<"If you could obtain them"> <"Corydoras hastatus"> definitely will breed in harder water, and they are even cuter than <"Corydoras pygmaeus">.

Again just my personal opinion, but the best of the smaller Corydoras spp. for hard water is <"Corydoras panda">. They will breed in our tap water (<"about 18 dGH / 18 dKH">).

cheers Darrel

 

[fredi]

Hi all,

Away from fish <"like Parosphromenus spp">, maintenance is often fine in the "wrong water".

Because I'm both <"incredibly lazy and tight with my money"> I like to keep fish that produce at least a trickle of fry (with minimum intervention) and usually soft water fish don't breed successfully in harder water.

<"If you could obtain them"> <"Corydoras hastatus"> definitely will breed in harder water, and they are even cuter than Corydoras pygmaeus.

cheers Darrel

Not that I have any connection with them (other than occasionally purchasing fish over the last 30+ years), but wholesale tropicals usually have some of the less common fish (especially catfish) in stock

 

[Calamardo Tentaculos]

Not that I have any connection with them (other than occasionally purchasing fish over the last 30+ years), but wholesale tropicals usually have some of the less common fish (especially catfish) in stock

Good point. I am long overdue a visit there. Might source some habrosus from them in the future when I set up a new tank.

The only way to get softer water is either RO or rain.

Well, I already use RO and cut it with tap water to 150-170TDS. Yet for some reason my PH remains at 7.5. Is it because I cut it at close to 1:1 ratio instead of 10-20% tap?

I wouldn’t start messing about with your PH, it’ll cause more issues. You need to keep things stable.

I don’t think your water is the problem.

Yes, I do think so. It's definitely something else.

 

[dw1305]

Hi all,

I already use RO and cut it with tap water to 150-170TDS. Yet for some reason my PH remains at 7.5. Is it because I cut it at close to 1:1 ratio instead of 10-20% tap?

Basically yes. You need to reduce the dKH to a low level (some where around 2 -3 dKH) before <"the pH starts to fall">.

cheers Darrel

 

[LFNfan]

Would be interested to know how much food people are giving their corys to get a sense of how I compare.

I have cory Kanei, and feed them once a day or every other day, more or less an amount which I guesstimate as equivalent to the size of their eyeballs. So, five corys = ten eyeballs' worth of granules and or pellets. But I have never weighed food.

If I'm feeding brine shrimp or daphnia, I put in half a packet one day and half the next. That's probably feast time, or every fish for itself. The packets are the mini plastic bags with water plus the daph / brine shrimp swimming around.