I haven't had alot of success cycling tanks thru with Piranha, they are messy eaters that can leave alot of debris. Also they are small/soft scale fish and can fall to high levels of ammonia, nitra, and chlorine. Keep a close eye on the water parameters - frequent 20% water changes may be nessassary. Also don't be too over anxious to be throwing in new fish - let it cycle thru 1st then maybe 2 every couple of weeks. Your patients will be rewarded in the long run. Congrats on the 125 hopin' to see pics in the near future.