Have you checked your water quality yet? It's time to do it... before you start feeding.
Do you know that it takes approx. 4-6 weeks to get your filter running so that it removes the bad bacteria? Prior and during this time you will build up the ammonia and nitrite levels from overfeeding and if you are over crowded.
High ammonia is from a lack of filtration, too many fish and or a dirty pond. If you check your level and it's high you should do at least a 25% water change and then recheck your levels. If it is still high remove another 25% and recheck. Continue until your levels are down to zero.