What is the word meaning

an organism that grows only to meet the size of its container. The organism with this property does not outgrow its pot or pond, being genetically coded not to reach a specific size, but an appropriate, adaptive size without detriment to the organism.

I believe I heard it being applied to koi from a biological point of view. Alternately, it might have been in a lecture about micro-ecosystems. I'm' not sure if it was an adjective or noun.

No librarian, university or otherwise, has been able to help me.

Does anyone know the word or where to point me? Perhaps there is
a resource you know that might help me locate it? Like a rhyming dictionary, but for meanings, maybe?