I have a 55 gallon aquarium that houses one giant ‘red terror’ cichlid, 3 silver dollar fish and a catfish. I stirred up the gravel at the bottom of the tank and collected some of the muck that had settled down there. Then I imaged a drop in my foldscope. I used a glass slide and coverslip, and put doublestick tape on the slide first–total of 4 small pieces, 2 pieces stacked on top of each other, and another 2 about 2 inches away. This prevents the coverslip from squishing live animals. Then I put down a drop of ‘muck’, placed the coverslip and imaged.
Very cool discoveries–I saw several ciliates of some kind (paramecium?) and something that looks like a spider or a mite. What is it? I found out from Wikipedia that Hydrachnidia “are a group of mites covering more than 40 families and 5 000 species (Smith & Cook 1991) found in freshwater and marine habitats.” Maybe it is one of those.