Over the years of freshwater aquariums I've always used one of these. For a long time I only had the small size, but always wanted it a little bigger, so I prefer the larger size. They are useful for acclimating your fish from fish storage water to your aquarium water and placing them in the aquarium floating will also keep the water temperature stable. I've also found it easier to fish with an acrylic tank as they don't seem to see it as a threat unlike a net (so a small size would be handy). I recently ordered red cherry shrimp online and when they arrived I placed them and the clinging moss they were traveling in in this container to acclimate them and I managed to scoop out all the tiny shrimp (they are transparent and heavy see) without having to pump out street water into my tank.
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