A plastic tank cave
      in a planted aquarium

My 100 liter aquarium

For my tropical fish I made a new tank cave with big internal hollows and many comfortable holes. So cichlids found proper place for eggs , and after they made spawn it was easy to save their fry. Barbuses also could rise upto sufficient size from eggs due to mutual small holes.

Photo
      of an aquarium with big homemade cave. Plants, fish.
A cave in a tank