Shy fish

Question:

My pond is about 2mos. old. Test strips are green, slight higher ph. still in range. Pond was murky, fish would come out to eat. 3 Koi 4inches. My goldfish swim around fine, Koi hide under the plants, won’t come out anymore. I’m in Central Florida, raining alot lately. Also have started with a little string algea? clustering on around my 4 leaf clover tangle mess. This is where they hide. Crayfish moved in and a bull frog,are they any responsibility for my shy fish? Picture very small, unsure if it helps the clumpy algae is in the upper left side and lower right. Any help would be greatly appreciated. Thanks, janine