Years ago when I worked in an aquarium store we never kept bettas in a cup we always put one in each suitable tank (very peaceful and no fin nippers) with the others that lived in the tank. Then we just put a red sticker on that tank so we could easily show them to a customer. When each one was sold we replaced red sticker with a green one so we knew, at a glance, where they were AND how many to order. We may not have sold as many but they were happier and healthier when sold. We would never have even thought to put them in cups. Horrible now how they treat them.