Diamond tetras again... I give up...

[WinterRose73]

@BigBen Thank you, I'll have a look.

I almost hope that is the problem and then maybe I can actually fix it. ETA : just read the article...

I do a 50% water change once a week which includes gravel vacuuming so that should sort out any waste? Other than the branch and wood / java fern (which I do need to sort out) there isn't any other decor. There is no algae issue. The filter is an Ocean Free Hydra 20.

@Lee_k No, all my other tanks are absolutely fine. No issues at all with any of the fish. Perhaps the diamonds are exceptionally sensitive... I really don't know. I will retest from the tap with the high range and see what it says.


I am going to put the diamond to sleep. I've done the water change (60% or thereabouts) and it has started to swim in a corkscrew / spiralling motion and upside down. The last one did exactly the same thing. I think once it has reached this stage it is unlikely to recover?

Whatever is wrong with it, it has escalated from being completely fine this morning, to whatever it is that going on now, so that is different from most of the others which seemed to decline slowly and (other than one) did not exhibit the spiralling.

[WinterRose73]

Sorry to post again.... Just done the PH for the big 190 tank and it looks exactly like the tap test - that deep blue colour. Repeated with the high range pH just in case and that's yellow so not entirely sure what that result means?

Repeated the tap water with the high range and I think it's sitting around 7.8....

[Gingerlove05]

Sorry for your loss
The ph is 7.4.
If the low range reads 7.6, high range test needs to be done to see if its higher. If it shows 7.4, its 7.3-7.4, so easier to say 7.4
I only wish i could offer more advise on the diamonds

[WinterRose73]

Thanks @Gingerlove05. Sometimes I find it hard to tell the colours on the API tests as a lot of them are fairly close together...

[Redpanda]

Sorry to hear these diamonds not doing that well. I’m no expert, but seem to remember when researched my stocking options that diamonds preferred slightly harder water, and although really wanted them my water was too soft. Which is very similar to yours . But again am no expert and no idea how would that affect the fish ..

[SPACKlick]

I’m no expert, but seem to remember when researched my stocking options that diamonds preferred slightly harder water, and although really wanted them my water was too soft.

Think you might be thinking of a different tetra, Diamonds like soft, slightly acidic water. pH 6-7, dGH 5-12 sort of range.

[WinterRose73]

Think you might be thinking of a different tetra, Diamonds like soft, slightly acidic water. pH 6-7, dGH 5-12 sort of range.

Wessex Water has a dH reading, is that the same thing? And looking at the pH, even if it has dropped it should still be within their preferred area at 6.4/6.6. Or am I misunderstanding completely?

I've never ever experienced issues like this with any other fish. I know I've only been in this hobby for 4 years but still.... If I was losing fish in the other tanks then I would absolutely say something I was doing is wrong. And perhaps I am but I can't figure out what it is. But it is only this tank, and only these beautiful fish

[Martinspuddle]

@WinterRose73 do you have or you tried any Catappa and Guava leaves in your aquarium, may help with their health.

[plankton]

OK, it looks like the ph could be the culprit (thanks @BigBen), so do smaller water changes from now on.
"PH shock" is normally more to do with TDS differences, but the swing like that of a ph value is a heck of a lot from alkaline to very acidic.
What happens to the ph if you leave it for 24 hours? If it drops during that time then you may have to leave it before water changes (hope you have a big storage place to stop cats getting in ).

[BigBen]

OK, it looks like the ph could be the culprit (thanks @BigBen), so do smaller water changes from now on.
"PH shock" is normally more to do with TDS differences, but the swing like that of a ph value is a heck of a lot from alkaline to very acidic.
What happens to the ph if you leave it for 24 hours? If it drops during that time then you may have to leave it before water changes (hope you have a big storage place to stop cats getting in ).

Thinking about it, it's probably also why I can't raise Cory fry at the moment...