Can Daphnia kill babies?

[trisha]

I have a second batch of eggs laid on xmas day. They were transferred to another tank with an airstone. Some babies accidentally hatched early when we moved them but survived a whole week until the others started hatching. Now I have suddenly lost half of the hatched babies - and some babies still inside eggs are dead.
The daphnia seem to be hanging on to some of them - on their tails and gills??!!! and some eggs have about 10 daphnia clinging to them.
I have also noticed glassworm in my daphnia bags - and have seen glassworm killing daphnia - so that is my other thought????
Or could it just be because they are a weaker 2nd batch?
Also their tails are curling which I know to be a sure sign they are gonna die?
Any thoughts?

 

[edward]

Daphnia are filter feeders and cannot act as predators. My first thought is are you sure that it is daphnia that is attacking the larva and not copepods? If the daphnia is collected (which it seems to be the case given that there are glassworms in the mix) then I suspect that it is the copepods attacking the larva.
Ed

 

[jennifer]

I agree, Ed. That doesn't sound like Daphnia behavior at all! Trisha, can you try some other food source? Can you get live blackworms?

Regarding the curled tails, I noticed this when I had a mass die-off of larvae. In that case, I'm fairly sure that the culprit was a bacterial infection - when I applied an antibiotic, the deaths immediately stopped. I hesitate to ever recommend antibiotics, but if they are dieing off anyway, it might be worth a try. The product I used was a combination of nitrofurazone and kanamycin, and I used it at the concentration recommended for treating fish.

 

[trisha]

I had noticed these daphnia were larger than the ones from before but I know they aren't brine shrimp.
As to the babies - they seem to be getting a growth on the tip of the tail and dying very slowly, but they also seem to be sticking to eachother. Some kind of fungus I reckon?

I have hand picked out all the dead ones and put the good ones (only about 45 now) into another container with complete new water from the parent's tank.

I think the daphnia(?) I am getting is too large for them to eat so am worried they are not eating (not much visible in tummies)

Where can you get the antibiotics in UK? I have melafix and primafix - supposed herbal remedies for ailments. Are either of these any good to use in this case?

 

[jennifer]

Ed suggested they might be copepods - some types of copepods do kill larvae sometimes. To compare what they look like, go to Google photos and type in "daphnia" and compare to "copepod". If you have a hand-held magnifier, you might be able to see which they are.

Here, all aquarium stores sell antibiotics for treating fish. I don't know about the UK. However, if the larvae aren't dieing off quickly any more, (after you separated them from the suspect food) then it's probably not bacterial. I wouldn't bother with Melafix or Pimafix, personally.