Hi pherylit,
This is my first time posting ANYWHERE at all. I am also looking for more info on c. sharks. But I would if you don't mind like to answer your question: from what I have found so far on the internet and asking people about how big of a tank, at least 75 gallons minimum---per each fich. Seriously. I have five of them-sharks-that are in a temporary 38 gallon that are being switched to a 125 gallon-when it's done cycling-and it still isn't big enough for them. I have not an idea what I'm going to do with them then. I didn't do my research enough before I bought them-I just remember my dad having five of them in a 55 gallon that 'seemed' pretty happy. But now with all the information I have learned about them-they were not happy. So, I really don't want to give them back to the LFS, but, I don't want to 'mistreat' them either..........oh. my dad was babysitting them, so the owner actually had no idea about them; and the water was freshwater. I do need to make my 125 brackish/marine water also. I would suggest you maybe start to invest in a larger tank. After finding out really how big they get, I looked on craigsli$t and found one here locally. Reasonable price too. Hopefully I answered your question enough. Maybe you found your answer elsewhere here? Good luck to you!