3 week old fry wiped out overnight

[nicky]

So I woke up to a dozen dead fry, and over the next 24 hours, lost all 80 except for three battlers, which I have photographed before cull (poor things must be suffering)

Main parents in the breeding system all seem fine, one pair recently laid eggs and another pair are about to.

The fry have been doing very well, 5 days on BBS 4x daily and continuing on slime coat.

Tanks cleaned/wiped daily, 60% minimum daily changes while with parents, and about to be moved into a growout/fry tank with 200% dailies (just missed it!). RO with some added minerals (PPM 50)

No Amm, N03 or N04 detectable.

The fry that died very quickly showed no signs of illness, and many of those I found prior to death, looked drunk and slowly made their way to the bottom where the were on their sides within an hour of leaving the group.
Within 24 hours, they were all gone. All except three.

Furthermore, another pairs wigglers all dropped and died off overnight. Same system.

Here's what has thrown me. I have not introduced anything into the system for months, except the BBS. The pictures below look very much like ICH to me, but I could be wrong. Is it possible that the white spot is a secondary infection given what these guys have just been through, or is it likely this is what killed them all and these battlers are only beginning to show the symptoms?

I've already raised the temps to 30c and have just done a PP treatment.

Any ideas? Pretty devastating, especially the 3 week old babies!!

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[jeep]

This sounds like flukes but the photo's look more like Ich. Seems to be some sort of parasite infection. I'm going to consult with someone for more ideas so check back soon...

[nicky]

Thank you kindly. I'm having a bad couple of days over this and now have 3 pairs in the same system, all fanning eggs. I need to get on top of this asap, but more importantly, figure out how the hell it got in there!

I note that I had done a PP treatment 3 days prior to the deaths too, but nothing abnormal about dosage / exposure etc. Just the usual.

[jeep]

Tammy agrees with my thinking here. They are at the age where flukes could wipe out fry in this manor, although it's more common at 30 days. Your description is identical to how fry act when they are attacked by flukes or bacteria and it can happen overnight. The spots on their sides look bacterial. Even with your excellent water routine, flukes and bacteria can still be an issue at this stage of development.

The best way to treat fry for any possible infection is to treat the parents before they spawn. Even a mild solution of PP can damage gills in fry. I would pick up some Rid-Ich+ and treat the parents before the next spawn. Or, you could treat with Prazi, although there are some reports that flukes are becoming resistant. Or you can use formalin @ 1 drop per gallon. Formalin and Rid Ich can affect your bio filtration.

I would also suggest switching them from RO to straight aged tap. Fry do just fine in hard water and need the minerals, even though you are remineralizing already. I do this before they even leave the cone. You're already wiping the tank daily, which is an important step in fry development that many people let slide, so keep that up next time. And, I would increase water changes to 90%+. I usually do this twice per day for the first month.

Please ask if you have any ideas or questions...

[nicky]

Thanks very much, Brian. That is useful.

I do usually growout on harder water, but as the parents are all on a central system, I can't go changing the params. I guess after some treatments I will drop the surface level below the overflow and throw a heater and let the sponge take over, easing them into heavily changed growout water, separate from the main system.

I'm dumbfounded that an ongoing ich cycle has been going on all this time without me knowing it. System is aged, parents have never had a problem so they have only ever received preventative maintenance. It just decided to let loose now!? As for the flukes, I must have missed a window between PP, and somehow they got in.

I must say, it always feels sketchy when things go pear shaped right after BBS feeding starts! I am pretty surgical with the old BBS, using a loop to inspect the pipet for an egg, vacuum after every feed, no flow/filter, rinse sponge etc. plus I don't believe they harbor any parasites/bacteria except for some egg issues / Oodinium I think it's called?

I'm going to smash this ich/white spot first to get the cycle underway and try to sneak in a PP for flukes/anything else before the eggs hatch out. 1 Spawn today, and 2 yesterday, so 3 pairs with new eggs. Brutal timing!

Thanks again and please thank your friend, Tammy for me!

[jeep]

System is aged, parents have never had a problem so they have only ever received preventative maintenance. It just decided to let loose now!? As for the flukes, I must have missed a window between PP, and somehow they got in.

I agree. Timing can be a %^$$#, especially during a change in seasons with water supplies churning.

I know this looks like Ich but I think the nodes are bacterial. The Rid Ich is highly effective against most external parasites and can help with bacteria.

Again, your maintenance is great and you seem to know much about discus, so don't give up!

[nicky]

Thanks again, it's so good to have people here to lean on and discuss. Long time lurker!

I think I will give the Rid Ich a cycle then. Or something similar here based on the same ingredients.

I will never give up btw! You know how it is with this hobby!

[CliffsDiscus]

Oodium from the brine shrimp eggs. This usually starts out with a few fry spinning drunk and dieing, the later it's a total wipe out.
I see this sometimes on my fry what I usually do is to open up a new can of brine shrimp eggs, no problem. Wattley said that when he was
away from his hatchery and his son was at home where the hatchery was and if he was a few fry swimming as described, his word was to hit it immediately with 37% formalin this will stop it tracks right away otherwise it's a wipeout.
Your central filter does other problems, the fry growthrate, what looks like Ich. I do agree with Brian about the RO.

Cliff

[nicky]

Hi Cliff,

Thank you for your reply. Do you think this was indeed the brine shrimp eggs and a low level ich population was able to attack the weakened ones? Is oodinium transferred from the egg to the BBS / Water as I don't feed any eggs. I'm going to go and now read for a while about oodinium , at least to better understand it.

Re. the RO, it's only for the breeders. I've never had a problem before with the RO, but will think about adjusting the entire system back to harder water once spawns are well fertilized. I might even get away starting to mix more minerals into the system and still get good fert.

I'm going to try a different batch of BBS anyway, shame is it is the same brand. I must do some more reading on oodinium and get some other brands quickly.

[nicky]

Oh,"Oodinium is a genus of parasitic dinoflagellates" that causes Velvet. I'm not sure I saw any velvet like growth (the smaller, golden dustings) on any of them. Most of them were clear to the naked eye, only the survivors 48 hours later showed the white spots.

Oh the ups and downs of breeding fish. Gotta love it!

[jeep]

Good call Cliff. I didn't think of the bbs being the culprit. The spots do look parasitic but I dismissed for the bacteria theory. I believe Rid Ich will take care of remaining populations...

Nicky, which brand bbs do you use?

[nicky]

I use Inve. Will switch it out next shop online, trip to LFS tomorrow.

I'm going to give Paraguard a shot as it seems it is general purpose for both parasites and bacteria, and won't knock the bio in such a crucial moment of 3 breedings. It's a lot friendlier than formalin although Gabe from JWD recommends both. So there is always that backup. The last time I heard of Paraguard was during the pandemic when silly people started drinking it and it became a cleansing detox fad. Some mothers do have them!!

I really, really need that microscope asap!