13935
There was limited evidence that a reduced loss of catalase activity plays a role in the acclimation ; catalase activity did not differ after the pre - exposure period but was significantly higher in Cu - acclimated fish than in the control fish at T .
 Cu
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: Chemical 
Text: {0} 
Answer:
 Cu