We are wanting to add these to my freshwater aquarium, but don't know how many we should get. Don't know if there supposed to be just 1 or 2 or 6. I have plenty of room in my tank for whatever. Current setup, 75 gallon tropical FW tank, 2 HOB filters, keep tank at 77 degrees. Current stock is 5 Zebra Danios, 6 Bossemans (spelling) Rainbow fish, 2 Platys, 1 Dalmation Molly, 6 Albino Cory Catfish. We plan on adding 1 small angelfish, and 2 Siamese Algae Eaters, and that would complete our tank. Thanks for any advice!