In Animal Crossing, you can decorate your homes with your favorite furniture. 
But if you want to make your home unique even at Stardew Valley, you can download this free mod and make your home look exactly like your favorite animal crossing.

With this, you can change the furniture and decorations in your homes to a mermaid style.

Also, this free mod doesn't replace the original file. If you want to add a new item, you will have to download the original file and add it to the mod.