Today I was pulling a bunch of old spawning mops out of a box which over wintered outside. About three at a time were boiled (more and they get all tangled up). Debris was pulled out and the strands were separated first. Then hot water was run into the soup pot until the mops were an inch or two under water. When that was all really boiling, I would wander off to do something else (feed the chickens, sop the hogs, milk the cows...) When I happened back into the kitchen, I would turn off the heat, grab some hot pads and drain the hot water down the laundry sink, rinse with cold water, squeeze out the mops and reload with more mops to be boiled. The last load will probably be put on the middle of the fishroom (cement) floor and used as radiant heat. :)

Those acrylic mops (wind 100 strands around a book, tie one side together, cut the other end and float using a rinsed medicine bottle - that is why my fish have such great blood pressure) are used as spawning surfaces for fish who hang eggs on plants. Goldfish, rainbowfish and many killies immediately come to mind. They can also be used as shelter for LIVEBEARER fry and females in tanks too dark for plants.

I first had the soap pot outside with gravel. I still boiled it. That may have been a mistake in that it was coated (colored) gravel in some tanks I was cleaning up for someone else. I'd forgotten about the coatings. Oops!

Freezing will get a lot of critters. Some creatures and diseases have cysts (everything from Daphnia to Ich) and may be able to over winter in that form. Freezing and/or sun drying will work in a lot of cases. That is great on rests between healthy tanks.

One needs to know what they are combating. If one doesn't know their enemy well, boil them. ;)

Since your fry are doing well, it "ain't broke." Don't fix it.

Stuff found on the beach usually should be soaked. Use freshwater for marine shells, saltwater for freshwater shells. I always wonder what/who is still in there.

Better to soak than be sorry. This is where getting a couple of fairly inexpensive buckets (an "In" and an "Out" bucket) just to be used for the fish is good. I would bleach (outside in the shade) in the Out bucket so it gets cleaned up too.

If you have a bunch of aquaria, it may be worth your while to buy a couple rubbermaid 32-gallon trash cans for the purpose. I still use them outside, whenever the weather allows. (I'm gambling that no freeze at this point will freeze them very solid.) Tops keep the bleach in one and the sodium thiosulfate (the dechlorinator in all dechlorinators and in the photographer's hypo solution) from dissipating into the atmosphere. Most dirt, critters and kids can be kept out too.

After a couple summers, I feel safe storing water or raising Daphnia or fish in them. If they release plasticizers, I hoping (knock on wood) that those have leached out.