[1] It is kidney-bean shaped, and approximately 60–80 μm (0.0024–0.0031 in) long,[1] with bands of cilia.

[3] In marine aquariums, B. hostilis infects most teleosts (ray finned fishes).

[4] B. hostilis feeds on dead skin cells and can cause severe damage to gills.

[2] The infection can cause sloughing of skin, and congestion of the gills.

[6] The parasite spreads rapidly, and can easily transfer to a new host.