I really like Beengirl's suggested list. Pom Pom, sexy's, and a pistol/goby combo. That should be plenty of animals for a five gal
, and provide plenty of interest.
Kenya trees will go limp like that when stressed, but to give you an idea here, when transporting my tank, my Kenya trees were exposed to nighttime air temps as low as 45 F, at up to 60mph, for a half hour. They were flat against the rock and dried out to rock hard by the time I refilled the tank. They are now even bigger and fluffier than before. Tough to kill.
I'm glad you've decided to rehome the lion. Fish growth is not fully understood, but we do know with relative surety that it can be stunted by cramped quarters, with deleterious effects on health.
Plus his being there almost guarantees you can't add anything else. He'd eat anything small enough for that tank. Lol