Clownfish acting a little wierd

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I just got 2 false percula clowns (ORA captive bred ones), they are small maybe 1-1/2" long. The have been in my 20g quarantine tank for the past 24 hours. These are my first ever SW fish .

These clowns spent the entire day today swimming up and down against the two end panes of glass chasing their reflections around. Not just slowly but zooming around at high speed, to the point where I got concerned they would exhaust themselves.

I tried blocking out the ends of the tank with newspaper (the bottom and back are painted and for some reason they don't see their reflection in the front) but they still see their reflection in the ends of the tank. It is the same whether I use a strip light, room lighting, or no lighting.

Will they ever get tired of this?