That is just a side-effect of pressing Ctrl-T. Ctrl-T switches the textures from compressed to uncompressed and vice versa. The texture switch requires resetting the 3D environment and that is what actually makes the fishes shift positions. I noticed the position shifting with every change of settings that requires a 3D reset like that.
 | At almost 25 m long Liopleurodon was the biggest carnivore that ever existed. It had an enormous 3 metre long mouth which contained teeth twice as long as those of Tyrannosaurus. | Ronald Zaalberg, Creator of Fish Picker
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