How much is considered normal to be lost while keeping fry?

[MSBolognese]

How much is considered normal to be lost while keeping fry?

The reason I ask is that I´m having real trouble keeping my fry.
The pairs are spawning, they are keeping the fry for 7 to 10 days.
If I leave longer they end up eating the fry.
So from that moment on I keep them in a tank with sponge filter and heat.
Daily whater changes (~50%) and feeding 4 times a day.
It all goes well unting I hit the 30 day mark. Them they start to die.
I´ve been loosing 20 or 30 a day.
From what I can observe there´s no indication of diseases.

What should I look for?
Any help is appreciated.

[Keith Perkins]

These are classic signs bacterial issues. For sure you should up your water changes to at least double what you're doing. You should also be regularly wiping down all the surfaces inside the tank. What size tank are they in and how fry are we talking about being in that tank?

[MSBolognese]

I´m keep fry in 20 gallons tanks, then transfer them to 50 and 60 gallons when they reach a certain size.
The fry act fine. From the moment they got in the tank they never stopped taking brine shrimp and swim from side to side.
Yesterday I lost about 30 fry, so I wipped everything down with a new sponge, did a 80% whater change and today I found only one dead.
Feed and came to work. Will have to assess later how they are doing.

Anything else I shoul look for?

[John_Nicholson]

I lose less than 1% of my fry. If you are losing more than something is wrong. Gill flukes, bacterial issue, dirty water, overfeeding, ....something else is wrong. I would start by feeding a little less and changing more water. If you have a microscope kill a fry and check the gills.

-john

[MSBolognese]

Don´t have a microscope. Will try with a friend.

I´ve had a lab test the water and it´s fine.
Will try to reduce feeding and increase whater changes and maintenance.

If I have a bacterial issue, what would be your suggestion?

Thank you.

[Keith Perkins]

Increased water changes and maintenance are the recommendations for nearly all the suggested problems. Once a bacterial issue takes hold it's not something that's quickly or easily resolved. You usually end up losing more than half the fish and often negatively affect many of the rest. Don't so much judge how bigger WCs and tank wipe downs affect this batch but how you do going forward with future batches.

[MSBolognese]

What would be the correct protocol for a tank with fry?

[John_Nicholson]

Basically it cannot be too clean. Do not leave uneaten food in the tank. Change lots of water, keep the temp at 82. I also never let the room get completely dark.

-john

[MSBolognese]

Would you say that in order to keep the tank not too clean, as you said, I should scrub it down every other day and do 80% changes daily?

[John_Nicholson]

Since you are having issues that would be a good place to start.

-john

[MSBolognese]

Ok John. Thank you all for you feedback.

Got a couple of pairs that will have free swimmers this week, so I´ll try again.