So i was looking at my tank and everything seemed fine! fish swimming around and than i spot that my cleaner shrimp dead... i think its been dead for at least 3-5 hours cause zebra was eating it.. I checked ammonia and it was like 4ppm.... I panicked and didn't know what to do, i made a 50% water change... I don't know what else to do now.,.. Can the ammonia spiked cause of the dead shrimp??? i did add the firefish yesterday.. but i don't think that caused the spike...what else can i do to treat this