Lizzie Simmonds and Andrew Willis won golds and there were two medals for Fran Halsall as British swimmers enjoyed a successful first day of the Mare Nostrum meet in Canet-en-Roussillon.
Swimmers from the British Gas ITC teams based in Loughborough and Bath combined for seven medals in total, with Loughborough's Simmonds taking the 100 metres backstroke in a time of one minute 00.71 seconds for the first of the day's two golds.
It was immediately followed up by Willis in the 200m breaststroke, the Bath swimmer touching first in 2min 12.66secs.
Loughborough's Halsall recorded the first British medal of the day in the 50m freestyle, finishing second behind Sweden's Therese Alshammer in 24.92secs. Amy Smith was fifth in the same race.
Halsall followed that up with 100m butterfly bronze in 58.97secs, 0.44secs behind winner Ingvild Snildal as the Norwegian edged out Canada's Katerine Savard.
Bath's Chris Walker-Hebborn edged out Loughborough's Liam Tancock for the final place on the podium in the men's 100m backstroke, finishing just over a second behind Camille Lacourt of France. Australian Ben Treffers was second.
The remaining British medals went to Loughborough duo Caitlin McClatchey and Jo Jackson in the women's 200m freestyle and 800m freestyle respectively.
McClatchey was edged into third by Holland's Femke Heemskerk as Camille Muffat of France won the 200m in 1:54.66, the fourth-fastest time ever.
Jackson finished in 8:40.05 in the 800m, behind Mexican Kristel Kobrich and second-placed Chinese swimmer Yirong Bi.