Jac, it all depends on what size the jam jars are, I'm not sure how "jam" jars got brought up specifically, but there are different size ones. Breeders regularly keep their maturing males in smallish containers as it's unreasonable to expect otherwise when you're dealing with 100's of fish. You say anything under 1/2 gallon is totally unacceptable, then you admit to useing 1/4 gallon. I assume you do plenty of water changes and keep the water quality good, so I'm sure your fish are just fine, hopefully others will do the same when using smaller containers. I'd rather have people use small containers but do enough water changes to keep the quality good then to have people use larger containers and think they never have to change the water (or rarely do). Jars ARE different from the cups in stores if they are larger than those cups and the water is changed regularly (the ones in stores are rarely if ever changed).
Linda
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