Because I have a breeding pair of cichlids in my 75g community tank and I've not moved them into a breeding tank, it's natural that some fry will make it but most won't. For those fry still darting around, it can be difficult to vacuum the sand substrate.
I like to keep my sand pretty clean and I'm prety careful when I'm vacuuming around very little fry because 1) they aren't easy to spot and 2) they don't move near as quick as larger fry. Thus, it's easy to suck some of them up and not even know it.
When I do vacuum around them, I use my PEX vacuum process. Though I've improved upon that method a bit (I've drilled a hole in the top of the bucket that I run the PEX hose through instead of using the binder clip), the basic process is still the same. The obvious concern with this method is ensuring that any fry that do get siphoned don't subsequently get carried off to the sink via the Python. I could probably address that also in a few ways, but I don't intend to.
Needless to say, each time I PEX vacuum near the fry, I always check the large bucket before I empty it to make sure that any fry that did avoid the Python don't get tossed. Much to my surprise, this very thing happened the other day. After finishing up with the tank maintenance, I set the bucket on the counter to look for fry. I not only spotted one darting around, but there were 5. YES, 5!!!
Good grief, my vision must be getting worse because I clearly never saw them when I was vacuuming and I really am quite careful. I actually didn't see them in the bucket until they moved. I use a 5 gallon bucket and the good news is that fry will typically swim away from the center of the bucket. There is usually no more than about an inch of water left once I turn off the Python, so it's easy to just stick a finger in and run it around the perimeter of the bucket. Fry will move away from your finger, so then you can spot them. Because my bucket always has sand in the bottom that gets sucked up during the vacuum, it's even harder to spot the fry sometimes. Nevertheless, I had to get them out of the bucket and back to the tank.
To do this, I use a small Solo cup. This works well to "herd" them in and then transfer them back to the tank. As confident as I am that I rescued all the fry that were in the bucket, I'm not as confident that I didn't vacuum up some fry that weren't whisked away by the Python. That saddens me becuase I know the probability is pretty low that only 5 fry were vacuumed from the tank and they all avoided the Python.
The Cichlid Room Companion
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American Cichlid Assoc.
African Cichlid Hub