high mortality rate on juvenile L66 first feeding

[GoldWing]

Hi all, some wise advise and help needed.
The first week after hatching i am facing a high mortality rate under the juvenile fish L66.
It almost looks like they have problems making the transition of feeding of the youlk sack to
feeding on there own digestion. I feed them verry fine artemia substituut powder, and "sera plankton tabs", and a piece of sucherinni.
I would say i loos about 30% of my initial number of the jong fish this way.
The fish look al healty, the fines ar formed perfect.
Can someone pleas share with me , his way of working, the timeline, witch food to serve after hatching and using up the youlk sack. Need the road to succes, hate it when dey die on me.
thanks

[Barbie]

Are the fish in the parent tank? What were you feeding the parents? I have had this issue a time or two, but it was usually related to temperature or water parameters, not the actual transition I attributed it to. Another issue that we discovered plagues fish at this stage can be chilodonella or oodinium parasites. There will be no visual clues other than a little bit of fraying on the membrane between the rays of the fins, if even that. Examination of the fry themselves will show signs though, especially a weakened or nearly dead one. Do you own a microscope or know someone willing to use theirs to have a look?

Barbie

[GoldWing]

i own a pretty good microscoop, i wil do some investigation.
The symptomes at the end always looked like swolen abdomen, that is the reason i tought it was related to the feeding. i could be verry wrong

[GoldWing]

The fish are in the same tank as the parents, but in a seperate container, with an actif flow of water from the parent tank. I feed the parent various , frosen food liken mysis and bloodworm as algea waffels and divers granulate.
Some aditional info to clearly outline the problem, while I wait for my next victims for a microscope examination. I am verry courious about the tip that parasites could be the killer, wil surely investigate.
The nests usualy have around the Thirty pieces, I lose the most fry in the first few days after the yolk is used up, easily ten of each nest wil die. I have always had to deal with large losses around this period and only with L66, the L46 do not have this problem.
Once the youngsters begin to color slightly darker, especially the belly region, they seem to get through. The ones that die, keep having light collourd belly's, almost like the youlk did not transite to a digestion system. Usually there wil be about twenty young per nest left over. If murphy wont work against me, there wil be a dead one to investigate tommorow.

[pleco_breeder]

I have to agree with Barbie. I had never seen the sudden fry deaths that seem to plague a lot of breeders till a couple years ago and it nearly drove me crazy looking for the answer when it happened. All the breeders in my system appeared healthy, but all of the fry started to die within the first month. After checking hundreds of fry under the microscope, I finally decided to break down and buy a quality dissecting microscope. The very first fry had obvious Oodinium on the gills.

The system was treated with a commercially available malachite and formalin mixture, and the deaths stopped almost immediately.

I've still never seen anything I could attribute to temperature or chemical parameters in my pleco tanks, but it wouldn't seem completely out of the question. I have seen it in my tetra breeding tanks.

Larry

[GoldWing]

There was indeed contamination in the thank, some of the guppy's that i have just to populate the mid layer of the thank had white spots on them. Because the adult L numbers look just fine i never made the link to the dying young. I have started treathment. Looking forward to my nest batch of eggs, and wil use my new expirience then from the start to protect the young juvs, curious if i wil see the difference.
Thanks for sharing the know how.

[Barbie]

The learning curve for these types of things can be quite stiff. I'm just glad we could help you solve it! There is always a need for more people raising these fish .

Barbie

[GoldWing]

just one observation i did make, that rased a question...
There are two small containers in the parrent tank, they both get water from the parrent tank by airlift. Both contain one nest of young fish, who differ two weeks in age. The oldest one had a period of fisch dying and is now ok, and now the younger one has dead each day. Still they are in exactly the same water, exept the age,als is the same.Is it maybe in the first week or two that the young are verry receptive to these things, just like they are verry resiliant to sickness as they get older?

[Barbie]

Exactly. They go from just absorbing yolk sacs to having to intake enough nutrition and oxygen to support themselves and the parasites can tip that balance very quickly.

Barbie

[GoldWing]

Had no more dead young fish sinds last post. Question, how do i go about next time that i got eggs? What is the best way of working?

[Barbie]

If you have treated the adults, there shouldn't be parasites present in the tank to worry about.

Barbie

[GoldWing]

Since my last post, have treated my tank setup with The FMC medicine.
Done it four times with interval of four days.
After this i had two nests of L66 in a row.
But the problem persists. Each nest has a few dead (5-10pc), each time al goes wel until they start feeding on their own, then a few days with dead youngsters one or two each morning, and then the critical fase is over, and no more mortality occures.
But it stil is a mortality of almost 10% each time.
any ideas?

[Zeno]

When you have a lost of 5-10 % on each spawn I think this is quit normal.
This means when you have 30 youngsters, you are able to raise 27 of them.
Good job !

Zeno

[GoldWing]

ok, i dont have a problem looking at it that way. i am verry lucky to be able to breed and enjoy the hobby at all. It is the question for me, what is the structural problem behind it? why is a reoccuring event? i want to learn.

[Zeno]

There are various possibilities such as birth defects to the digestive system, fish that cannot relieve etc ... If you really want to have more certainty about it, which doesn't mean at all that you can prevent this in the future, then the dead fish must be viewed under the microscope by a veterinarian.

[GoldWing]

I am inclined to believe that a certain % of death toll is indeed natural.
But why is it always with the L66 species, and for example not with the L46. These are in the same tank rac and the same water in my setup. No specific death toll there...
Have other L66 breeders the same % of scrap each time, no exeption.
Or do they also breed perfect nests of L66 no death toll, just want to know what is average....