They resemble several Norcrest pieces I have seen, but I did not find one exactly like these. The item "Vintage 50's Norcrest Hanging Ceramic Wall Plaque Fish & Bubbles" is in sale since Friday, May 25, 2018.
This item is in the category "Collectibles\Fantasy, Mythical & Magic\Mermaids". The seller is "bbsestateliquidation" and is located in Aberdeen, South Dakota. This item can be shipped to United States, Canada, United Kingdom, China, Mexico, Germany, Japan, France, Australia, Denmark, Romania, Slovakia, Bulgaria, Czech republic, Finland, Hungary, Latvia, Lithuania, Malta, Estonia, Greece, Portugal, Cyprus, Slovenia, Sweden, South Korea, Indonesia, Taiwan, Thailand, Belgium, Hong Kong, Ireland, Netherlands, Poland, Spain, Italy, Austria, Israel, New Zealand, Philippines, Singapore, Switzerland, Norway, Saudi arabia, Ukraine, United arab emirates, Qatar, Kuwait, Bahrain, Croatia, Malaysia, Chile, Colombia, Costa rica, Dominican republic, Panama, Trinidad and tobago, Guatemala, El salvador, Honduras, Jamaica.