A 100 wind mop which can be used as a floating or bottom scatter mop.

The photo shows it to be hanging by a couple of threads so its a floating mop. Just trap a couple of threads in the cover glass.
Just drop it in a tank & it sinks to the bottom to act as cover for newborn fish. As an added insurance drop the water level to within 2" of this layer which reduces the time the newborn fish need to find cover before the female eats them.

Don't knock it 'til you try it.

I'm a long term killie breeder, I admit it. A killie breeders main tool is a spawning mop. Livebearer breeders will wonder what a spawning mop is & why should I be bothered with it as I'm breeding livebearers.
For killies this mop acts as a recepticle for eggs which are picked off & incubated in seperate containers. For livebearer breeders it has other benefits. For a start I place brood stock in bare tanks 15" square & only clean the front glass. This is the old way of breeding livebearers, the old books teach you this. Livebearers eat algae & any other foods found therein. Plants are important to get rid of nitrate & offer a small area for nitrifying bacteria to colonise. They play a big part in my fish house as it is fully open to natural daylight.
For livebearers a mop is useful in two areas; one being cover for new born fish; two for filtration.
Cover for new born fish.
It's a well known fact that certain species of livebearers eat their young with gusto regardless of how well they have been fed. I remarked to Ivan Dibble that I had a sole female Brachyrhaphis terrabensis from a Panama collection which I had collected over 20 young which were growing on well. He remarked that this species would suck the babies out & eat them if they could bend that far.
I was lucky in being around near the time she dropped but the tank was heavily populated with floating spawning mops & sunken mops to provide a complete layer of the tank base.
I have dropped Brachyrhraphis cascajalensis (wild fish) in a similar way successfully along with Zoogoneticus quitzeonensis & loads of guppy forms.

Filtration.
How can a mop be a filter? A mop contains masses of fibres under the microscope. These fibres are surface area. This surface area becomes a home for nitrifying bacteria. The greater the surface area the greater the amount of bacteria the tank has available to manage the disolved metabolic wastes. A mop contains a huge area & becomes a great big colony for nitrifying bacteria. It has no container restraints & has a good flow of water over it (providing you have good aeration) which maximises the size & productivity of the colony.
They also attract heavy wastes. On a regular water change cycle you can carefully lift the mop & syphon this heavy waste off. Be careful though as young tend to congregate this area.
To clean the mop out is easy, just hold the mop between your palms & rub hard then squeeze it. Only use water from the tank to do this to preserve the colony. Fresh or cold water will kill your colony off.

Their is no doubt in my mind that mops are very important to the livebearer breeder.

How do you make a mop?
It must be 100% acrylic fibres to start with. Nothing else should be used. This is very important. Dyes are also important & should be tested for leaching by soaking.
Satisfy the above criteria & you are ready to wind a mop. Take a book at last 10" (25 cm) wide. You can wind as many turns as you need but 100 does the job for me.
Cut the threads & take two to tie the mop together by putting the lengths on your leg. Put the two tie lengths in the centre of these lengths & tie off tight. Again, loop the ties round the cord & tighten & tie.

So easy, so, effective, so try it for yourself.