Hyperiid amphipods (small crustaceans) of the following genera parasitise Agalma elegans:
They are found mainly in the nectosacs of swimming bells. Some go through up to 3 moults inside the body of the siphonophore, presumably eating it while they grow between moults.
The only predators so far recorded for Agalma elegans are oceanic filefishes of the family Monacanthidae.
Douglas Biggs observed in his PhD thesis: 'The filefish approached this siphonophore as soon as I had dipped a colony into the aquarium, and rapidly bit off every pigmented stem group (cormidium). After a few moments, a fish bit off the pigmented pneumatophore, but discarded it almost immediately. The filefish had no interest in the gelatinous remainder of the colony.'
Other predators might include: