25 % water change first.Increase water temp to 86-90 F, add salt I perfer Doc Welfishes at a concentration of 1 heaping tablespoon per 5 gallons, If unsure if it is a bacteria or a fugus start a treatmeant of melafix and primafix together at no more than 1/2 dose( if your tank is 125gallon treat as a 50 gallon tank) and follow the program for seven days. Arowana very hardy fish somtimes just needs a little bit of help. Keep in mind that after about 3-4 day it should start to get better but could take a couple months for full recovery. After your seven days do water change again install fresh carbon, wait a day or two then decrease water temp to 80-84 F. Use Cycle with treatment to help keep water condition good( add 10 capfulls the first day and 5 every day after for treatment period).
Good luck.
Disclaimer: I am not a fish doctor nor play one in real life - this technique has worked for me many times.[/QUOT
finishin my water change, starting mela/pima, removed my driftwood and found some white cloudy globs under the wood. thank u for the help, i'll keep ya updated
the arrow looks better today