The Vesaal
Location:Aya
You receive this quest from Ambassador Rialla, once the Nexus embassy on Aya is open. Talk to salarian Sorvis Lenn between the Taavetan and Resistance HQ to find out about the incident.
Lenn managed to tag the Angaran in question with an invisible dye. Use your scanner to find the guy in the training area of Resistance HQ (where Cora usually hangs out).
Talk to him to learn about the Vesaal, and the strain it places on his people.
Commiserate, then return to Rialla. Whatever you suggest, she vows to take it to Tann, and the mission completes with an XP reward.