Things are going to be fishy in the next episode of "Grimm" season 5 titled "A Reptile Dysfunction." A tourist's death has alerted Nick and Hank of the probable existence of a monster in the depths of a local lake.

The promo for the episode teases that "a deadly monster lurks in the deep" and before more people get killed, Portland's best detectives spring into action to stop the menace that prowls below the water and preys upon unsuspecting day-trippers.

The "Grimm" season 5 teaser provides a glimpse of the waterborne monster, which turns out to be a human that can transform into a deadly fish at will. The promo also hints that the new enemy won't be easy to get rid of.

"We need your help for what's coming," Meisner tells Nick.

What Portland is dealing with is something they haven't got a chance to contend with before, and they will have to bring out some bigger guns to take this baddie down.

As Nick finds a way to stop the killer creature, the detective does not take his attention off the Wesen Uprising. This "Grimm" season 5 installment will, in fact, show Nick the whole picture of the growing unrest. The synopsis also teases that Nick will be taken to the Portland operations center of the secret government agency, which may be the same group responsible for the warfare that continues to eat up the affected cities.

Meanwhile, the new "Grimm" season 5 episode will continue to follow Capt. Renard as he continues to back up a mayoral candidate.

Fans can also expect a follow-up to that cozy Adalind-Nick moment in the previous episode. The two might actually be a couple in the near future and not just formerly estranged individuals compelled to stay together for their baby. This should get interesting with Juliette -- or her killing machine of a doppelganger -- back into the picture.

"Grimm" season 5, episode 8 "A Reptile Dysfunction" airs Feb. 5 at 9 p.m. ET on NBC.