Marine Fish Capacity in 135G

Question
Hi, My 135G fish only marine tank has been set up since April 11 and currently have 12 fish. Water params are normal with water changes every 10 days. I have lost 2 fish in a 2 week period that symptoms show a possible internal parasite. This past weekend I purchased a blue strip butterfly and within 3 days he was dead. I am concerned that I might have too many fish in the tank that the new fish are getting stressed out. Can you give me a rule of thumb on number of fish per gallon. I know there are other factors involved as territory, type and size. I'm getting very frustrated that I can't keep a new fish healthy.

Answer
Hi Ron,

Sounds like you are doing everything right, therefore don't beat yourself up too bad. : )

Many larger wild caught species of saltwater fish, including the Blue Stripe Butterfly are much harder to introduce to an aquarium, i.e.  some won't take to living in captivity, in the confines of an aquarium, no matter how well the aquarium parameters are. Many species of butterfly fish including the Golden Semilarvatus Butterflyfish do require large aquariums, this particular butterflyfish is recommend to be kept in a minimum of 180 gallons.

Regarding your limitations, as far as how many fish for a 135 gallon aquarium, well this would depend on the species of fish. For large compatible fish, I'd say between 5 to 7. For much larger compatible fish 2 to 3, and for small compatible fish, possibly a dozen or so.

I also recommend to purchase captive bred species, when available. I also recommend to quarantine all fish prior to introducing them into your main show tank.

I wish you success with all your future saltwater aquarium endeavors.

Happy New Year.