How to increase the survival rate of guppy fry?

[biofish]

Hello everyone! I’m here to tackle a mildly annoying issue.

I have 4 adult female guppies, and every month like clockwork, they dump a load. My ladies have never given me large batches, bless them, so by the time I notice and take them out I only get 5-20 with the average around 12.

But that’s not where my issue lies.

I have 4 tanks dedicated to fry. 2 one and a half gallons and a 3 gallon for my newborn newborn fry. And a 10 gallon (soon gonna upgrade to 20) for them to grow out in with older batches of fry. And then when the fry are plenty big (I take no risks because my zebra danios could easily eat fry that I thought were big enough. And my first couple grown batches disappeared because of this so the danios have since been removed. It was a horrifying realization that the danios could eat something so big) i gender them and put them with the respective adults. Every tank has a heater, all 4 of the baby tanks get fed 4 times a day with crushed flakes that are crushed to accommodate their different sizes.

And yet, despite all that, I have fry that mysteriously vanish. I can never find their bodies. All I know is that I should have many more guppies than I currently have. A lot more. I was wondering if they were eaten by their elder siblings in the 10 gallon. So it’s a constant game of removing fry just as they are big enough to go into the main tank and keeping all too small babies in the newborn tank until they are big enough to upgrade.

My eldest batches that survived the zebra danios often die of the guts falling out (ladies were pregnant from wherever they came from before I got them and probably inbred). This problem hardly effects my younger batches that I purposely bred. And I’ve noticed that the guppy fry who develops black back half of their body, have an absolutely abysmal survival rate. I think I only have 3 (black back babies) total that made it to the adult tanks (One of which was born with crooked spine and can’t be bred but I still love him a lot).

The 10 gallon has its share of hiding places. It has plants, tall and short, as well as a hollow tree trunk like decoration. None of my guppies adult or baby really use the caves/hollow decorations though. They no longer seem to mysteriously vanish in the adult tanks except for the older batches getting that gut pouch out their rear.

Any advice?

There are no other fish in the tanks except Cory catfish in the adult tanks

 

[April_ht]

Do you have gravel in your tank? When I had livebearers, I noticed the fry would hide in the small crevices between the gravel and be barely visible. There is also a chance they passed and the body was eaten by the other tankmates, or swallowed up by the filter intake if you're not using a sponge filter. Also, there's a good chance they were just eaten live, as in the past I have underestimated the size the fry would no longer be swallowed, just for them to disappear the next day.
If you're not using a sponge filter and have gaps where the fry can get into the filter, I would try replacing that with a sponge filter or covering the intake with a sponge or mesh guard. Otherwise, maybe try setting up a camera for half an hour or so next time you put the fry in there, to see if any of the bigger fish are chasing the fry. This could help you rule out the fact that they're being eaten or find out if that's why they're disappearing. Also, make sure the water chemistry is healthy and you're up to date with water changes, as this can be a big killer for fry due to the fact they're so sensitive.

 

[biofish]

I think my best bet would be the camera. I have a mesh over my filter to help prevent that fry from getting sucked in. I have spent wayyyyy to many hours trying to net fry out of filters to not do it. The longest one took me three days and three different people to finally get out. Guys, never put fry or a pregnant lady in a tank with a built in back filter. Just don’t do it. And yes I do have some pebbles as my substrate; half pebbles half sand. And the first time I accidentally squished a fry after they hid in the substrate I sobbed . Now if a fry wiggles into the pebbles I just send them a silent prayer that they survive in the adult infested waters until i am able to safely net them again.

That and water changes. I keep seeing people saying biweekly water changes for fry tanks but I’m not sure if they mean twice a week or every two weeks? I will admit I don’t have the most scheduled water changing practices. I think they typically get their water changes about every two weeks. Sometimes more frequently if I think something is wrong or I just get the sudden motivation to do it. I do 50% water changes each time. (And one time a fry took a ride in my siphon and I think my soul ascended as I saw the tiny movement right before I blindly dumped the dirty water on my plants. That poor guy got swept up and deposited in vacuumed-pebble-pitch-black-poo water. Wonder if he’s still around. )

 

[GaryE]

Older siblings will eat younger ones. Add to that your growout tanks are really tiny, and you will have losses.

But if you don't what will you do?

Rounded rocks scattered on the bottom, golf ball sized, and floating plants increase livebearer survival here, at least for the crucial first week. But it has been my experience that older siblings are more predatory than adults are.

 

[emeraldking]

Sometimes, you just don't see all fry clearly. Happens overhere as well. And then in a sudden, it seems there were more in the tank than I thought there would be.

But in case such fry die, the body will decay very fast. Most older siblings won't eat their younger siblings. But they may chase them.

With most livebearers (even guppies) that I keep at my place, the pregnant females will drop their fry in the tank of the adults. And those fry will be left alone by the bigger fish. Only those livebearer species that will chase and eat their fry, I get the pregnant female out of the tank and place her elsewhere. So, she can drop those fry and when she's done, she's going back to her normal tank.
It's also when you'd invest time to let the bigger fish get used to small tank mates, at some point, they start leaving those fry alone. But most people just don't want to invest that time. This works. And this is also why I am able to have a high number of fry in those tanks.