We do not know how dependably spottail shiners (not SFS) will spawn in a pond. Does anyone know of a pond where spottail shiners are thriving and positive that they are spottail shiners?. Spottails are normally river and lake inhabitants.
Spotfin shiners(SFS) are crevice spawners seeking cracks and crevices that are 1/8" to 3/16" wide. In the wild the spotfins usually seek tree bark that is peeling away form the trunk. In crevices 1/4" and wider the opening gets to be too wide of a crevice and is ignored by the spotfins. High production systems use artificial spawning devices for spotfins that are copies of or similar to hester dendy samplers.
http://www.hesterdendy.com/ http://www.ag.auburn.edu/fish/image_gallery/details.php?image_id=1703&sessionid=eb4e832e58fada 
