mysterious die-off

[judy]

well, I have no clue why, but every night for the past four days, about half a dozen young'uns have kicked it. and the batch has not been growing for about two weeks, even though being fed bountifully and eagerly eating chopped bloodworms-- they still look like they're three weeks old, and they're six weeks! water changes have been faithfully done, the water tests perfect, no temperature fluctuations-- it was a small batch of about three dozen snakskins, now down to 16... i finally dosed with prazi-pro today, thinking maybe it is some sort of intestinal parasite...
any thoughts from wiser heads than mine?

[Eddie]

Are you feeding just the chopped bloodworms? How much water are you changing? What is the general hardness of your water. Have you noticed any symptoms or just them dead?

[mmorris]

It might be useful if you could give us all your water stats - temp., ph, nitrate etc., water change regime (how much, how often, aged?), diet (what, how much, how often) and tank size. Like Eddie said, symptoms might be useful.

[judy]

no symptoms at all-- no strange swimming, no body twitches. They look and behave like normal little hungry babies-- but they are not growing. water test : temp 86, ph 6.8, ammonia zero, nitrite zero, not checking nitrate due to daily WCs and zero on both previous factors, water change twenty percent daily, vaccing bare bottom to remove uneaten food. filtration is one AC 50 with a small sponge covering the intake tube, and a sponge filter. Feeding six times daily, in amounts consumed in five minutes. feeding only chopped bloodworms.
there was just one dead this AM...
water is not aged, just treated with prime. I have never aged my water, have raised six successful batches prior to this, and have not been not doing anything different this time around...

[mmorris]

How large is the tank? For comparison, I do two 80% wc's daily on growing fry. I don't think 20% is anywhere near enough, but I don't know how large the tank is. I recommend you up the wc's and add one drop acriflavin per gallon of water. Do you age your water? If not, do you know if your ph fluctuates from the tap?

[mmorris]

feeding only chopped bloodworms.
...

I just caught this. You want to feed a mixed diet, with, perhaps, beefheart, flake, an appropriate sized pellet, etc. I recommend ordering some fdbw from Al (Brewmaster). Is this batch of fry from the same parents as the other six? Congrats on the other six, by the way. That's a serious amount of success.

[judy]

Hi-- no, this batch is from a brand new pair that I didn't even realize was a pair (nor did the LFS-- a good guy-- who swapped them with me for my mated pair of red melons, who've produced four batches. My red turqs have given two batches.) This new pair laid in the quarantine tank, which is just 25 gallons and is where the babies have remained since. The parents have long been removed to the display tank, where they are thriving.
I've changed out that small amount of water with the previous batches and they all did well-- there is serious over-filtration on that small tank. But I'm wondering if the WCs may be an issue for another reason-- it's after doing large (50% WCs) that the babies died overnight. Is it possible the WC raised the Ph (out of the tap it is 7.4) and the well-aged sponge filters dropped it quickly overnight?
I should probably try checking the Ph hourly over the afternoon and evening to see if this may be a factor...
The tap water is consistent in Ph in winter, though it can fluctuate in summer (and, since this city water supply comes from a natural lake-- one benefit of being a Canadian in a non-polluted, low population region, also gives me algae trouble sometimes in summer).
There are only 15 little ones left now, so major WCs likely aren't needed since I'm feeding according to the number of fish and there is so much filtration-- and with Prazipro you don't do a wc for seven days anyway.
It won't break my heart to lose this batch if that's what ends up happening-- but it would be good to understand the cause and prevent future occurrences, This is the first batch ever where I've had die-off. Occasionally, I've lost four or five babies at about the four week age, but never this...
Their second feeding today is fine flake. I'll continue to vary the food.

[mmorris]

Fill a bucket with tap water and aerate it. You want to check the ph in water without fish. I can't see how the sponge filters would affect the ph. What's the kh of your water? If the water has little buffer, then the ph would drop in the fish tank.

[judy]

ah. good point! will check it. also will do an aerated bucket. will report back in progress, if any. it's all very odd indeed. And I am not used to failure with my discus babies.

[judy]

did not do a WC yesterday at all, varied the foods slightly (chopped FBW and fine flake). this morning-- no dead ones.
hmm.
prazipro working on possible internal parasites?
no sudden change in water parameters, espy Ph?
i have no explanation other than these are the only two parameters I changed...

[mmorris]

So when you tested in ph from the tap, and tested the ph from an aerated bucket, what was the change?

[kaceyo]

If she's only doing 10% wc's, even a fairly big difference in pH of tap shouldn't have that effect.

[MostlyDiscus]

I agree with Kayceo here. 7.4 down to 6.8 over the course of the night will not affect fry. I had my ph drop from 5.8 down to 4.7 during the night and the ablino babies that were scattered about the tank seemed to locate the parents, HMMM:confused:. The fact that you put in the PrazziPro and seemed to help would tell me FLUKES.

Ed Mostman:p

[mmorris]

it's after doing large (50% WCs) that the babies died overnight. .

It would have been an abrupt rise if her water is gassing off rather than a change over hours. I haven't had much luck with prazipro and flukes. Some people double-dose but I don't recommend it on fry.

[kaceyo]

It would have been an abrupt rise if her water is gassing off rather than a change over hours. I haven't had much luck with prazipro and flukes. Some people double-dose but I don't recommend it on fry.
Right, I thought it was 10% wc's.

[judy]

I didn't do an aerated bucket because (I now realize) all my airpumps are occupied servicing sponge filters. but there has been no additional die-off and I haven't changed water for the second day in a row. If they do make it, I hope this hasn't stunted them badly. The parents are really quite nice.

[judy]

Still no more dead. Must have been something the Prazi dealt with...