I had 24 tinfoils in a 240 with my rays. They got to about 5 inches or so before they got the taste for them. Very frantic at feeding time.
I had a 55 gallon in high school with 6 discus and 200 tetras. I worked at a shop and got paid in store credit if I wanted, also got everything at cost. It was way overfiltered and all fish were fine until discus got a taste for tetra when the got big enough to eat them. After that it was only headlight taillights and red eyes left, all the skinny species were taken down. Wish they had camera phones 18 years ago, it was a cool tank to watch.
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