The Echeneis opens with a tail slap against Kiryu. Kiryu is next. To Vint's question about SLA's, I would not count SLA's as needing concentrations checks underwater, because non-magic casting classes have SLA's and I don't want to punish them for not spending feats to improve their concentration. I would read the note at the end of aquetic terrain though. "Some spells function differently subject to GM discrection". Water conducts electricity better than air does.
Turn Order
Echeneis-19
Kiryu 17
Eko 13
Variel 11
Maura 8
!roll 1d20+5? #Tail slap vs Kiryu
!roll 1d4+1 #Dmg vs Kiryu