the small one will grow fast as long as you leave it. If your main tank can handle it, I'd leave it in there. Give it 3 weeks or so. You should see it start to gain size pretty quickly. If you have a separate tank for them, divide it and put both fish in. Leave them like that for a while. I left my female and male for a month, wasn't good enough. I just need to be patient. You'll see them start to clear around if you indeed have a male and female. If they do start clearing, leave divider up for a bit. I like to build their bonds in a big community tank. Seems to work better.
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