Pristella tetras

[noelberg]

I noticed that some of the pristellas at my lfs are more see-through and have a deeper red tint in their tails. The others are more silver-colored. Anybody know if there's a species difference or if the tails of some of my pristellas will get brighter red?

Also when I only had 2 of the more silver ones, they almost always stuck together, now they "school" less since there are 3. I plan on adding more, but didn't want to add too many too quickly.

Thanks!

 

[Lateral Line]

The commonest Pristella is Pristella maxillaris, the X-Ray tetra. The common name referes to the fairly transparent nature of the fishes body. What you are probably seeing is sexual dimorphism. The swim bladder, (large silvery organ), in the male is smaller and pointed to the rear, the females is round. Generally males have slightly better colour as well, but in this species the difference isn't great. Females, as with most tetras become deeper in the body and when viewed from above, noticeably wider.