British swimmers dominated day one of the Barcelona leg of the Mare Nostrum series securing a haul of 13 medals, including five golds.
Double Olympic champion Rebecca Adlington was the pick of some strong British performances as she won gold in the 800m Freestyle with an assured performance and a championship record of eight minutes 19.86 seconds.
Adlington led from the front and built up a lead of over two seconds at the halfway stage, finishing strongly ahead of Spain's Mireia Garcia Belmonte, the world short-course silver medallist.
World open water champion Keri-Anne Payne was fourth in 8mins 41.50secs.
Hannah Miley and Aimee Willmott claimed gold and bronze respectively in the 400m individual medley. Miley was chased closely by Willmott until the Scottish swimmer pulled out a lead at the end of the breaststroke leg. The Garioch swimmer continued to stretch the field and touched in 4:34.68, Belmonte took silver and Willmott the bronze in 4:40.12.
Miley secured her second medal of a busy night at the Sant Andreu Club Natacio when she won bronze in the 200m breaststroke after she was narrowly squeezed out of the silver medal. Gold went to Marina Garcia of Spain, Miley the bronze in 2:28.49 with Stacey Tadd fourth.
Georgia Davies claimed gold in the 100m backstroke in 1:00.87 while fellow Swansea ITC swimmers Jaz Carlin and Jemma Lowe were both third in the 200m freestyle and 100m butterfly, respectively.
Chris Walker-Hebborn posted his fastest time of the season to win the 200m backstroke (1:59.04), European silver medallist James Goddard won the 200m individual medley in 2:00.95 while Stockport ITC team-mate David Carry was edged out of the 400m freestyle by 0.32secs by Sebastien Rouault, finishing second in 3:51.96.
Michael Jamieson was second in the 100m breaststroke dominated by world championship bronze medallist Cameron van der Burgh, the Briton touching in 1:01.17 with Craig Benson fourth.
Rob Pavoni and Matt Johnson claimed silver and bronze in the 200m butterfly.