[Zbrafish] Question on Swimming Behavior

[Rachel]

Hi all,

I've been culturing D. rerio for the last 4 months in 120L glass
aquaria on flow-thru water exchange system.

Lately, I have noticed that some of my fish (mostly gravid females)
have been swimming with their body in an odd position, nose-down-
caudal-fin-up ( similar to a '/' position). In addition, the swim
pattern is not a fluid motion but more of a quick jolting forward
movement. I have noticed this behavior in adult fish only >90 dpf.

WQ: Temp 26-27 degrees, pH 7.96-8.05, D.O. 96% saturation
Feeding regime: 24hr artemia a.m. and p.m.; Tetratmin Flake Food at
noon.
Stocking density: <5/L

Any thoughts on what could cause this behavior and what it could mean
for my population?

I appreciate your time,

Rachel Pryor
Student Services Contractor, USEPA
pryor.rachel from epa.gov
850-934-9279