Tank too full? Brown Algae??

[F1shmom]

Hi, I have one Koi betta in a 5 gallon tank. I wanted to give him some good hiding spots and places to explore but I wonder if my tank is too full. Also, should I scrape this brown algae off his little pineapple house. Thank you in advance for the help.

 

[Circus]

You can rub the algae off, it won't hurt anything. You can always move your silk plants a bit more to the edge, so the fish has the option to either swim or hide. You can try spreading the leaves a bit.

 

[Retired Viking]

You should consider replacing your fake plants with real ones. They will help the quality of your water. There are plants that are easy to take care of like moneywort , anacharis and moss balls