You used a lot of fertilizer? Heavy in Nitrogen? That will overload a pond faster than you can say I hate algae. Any runoff will take all that excessive nutrients right into your pond. If I was your pond manager I would wait to see if warmer temperatures do the work for you. Judging by the photos it is not all that bad. If that does not do the trick I'd go with barley straw or beneficial bacteria. Both should break the algae cycle you may have inadvertantly started by fertilizing. I would not use chemicals. I would not introduce tilipia. Neither one of those will break the cycle and you may have it back really fast. Target the algae.
