I agree, its too exposed for the fish to feel safe enough to breed, so cover back and at least one side. add more wood.
re the other discussion I think tds can be a factor and you dont want zero tds, its not just about pollution, there are some chemicals the fish need which is why if you use pure RO water , for example, you ad re-mineralise to put the right chemicals in the water. but if your tap water is very hard (like mine) nthen the tds does need to be reduced by rain water or RO. a TDS measuring wand usually under £20, is much easier and cheaper then chemical testing kits.