If the OP even cares anymore...
Arowana don't really care about the depth of the tank (although personally I wouldn't go any lower than 1.5ft) but more about the total area they can swim in; much like stingrays. Since they stay near the surface of the water swimming back and forth, standard tank sizes are not really suited to house silver/black arowanas as most commercial tanks do not have the width they need to properly turn. This is because silver/black arowanas may grow up to 4ft in length (but average closer to 3ft in home aquarium), so for an absolute minimum I would go no less than a 300g for a single adult specimen (although there are people who keep them in 180g and 240g). There are two main reasons for this:
1) Arowanas need to be kept in groups of 3 or more. While a pair can work, it usually leads to one arowana being extremely dominate while the other gets bashed hard. Thus, the more arowanas you have the more spread the aggression is.
2) Arowanas are extremely active fish and almost always stay near the top of the water column swimming. Even if you get a docile pair, a 300g is barely enough for one to swim back and forth assuming it only grows slightly past 2ft (remember they average 3ft). Thus, if they feel as if they are running out of space (or stressed out in any way) arowanas tend to jump... a lot.
Now, a 300g will work great for a few years for all the fish in the picture because Arowanas grow slower (length wise) once they hit 12-15" and put on girth. However, the key to keeping them healthy would be a beast of a filtration system. Multiple canister filters or one large sump will be required to keep the water pristine.
Theres a reason for this. Because they speak up and make themselves and their ideals known. Theres a line between being a complete tool and speaking your mind. I'd see no issue with talking to the owner about the fish and his future plans and making mention the tank is way to small for an aro. Yelling and screaming probably won't get you anywhere but kicked out, but I too would say something in this instance because that's not right. Its one thing to over crowd a tank but have perfect filtration, its another thing entirely to keep a fish capable of growing past the width of the tank its in.Hello; Again I suggest you do some research. Around my area they have influenced the animal care laws quite a bit.
Amen and thank you.Theres a reason for this. Because they speak up and make themselves and their ideals known. Theres a line between being a complete tool and speaking your mind. I'd see no issue with talking to the owner about the fish and his future plans and making mention the tank is way to small for an aro. Yelling and screaming probably won't get you anywhere but kicked out, but I too would say something in this instance because that's not right. Its one thing to over crowd a tank but have perfect filtration, its another thing entirely to keep a fish capable of growing past the width of the tank its in.
Thank you and I am still interested. A few people mentioned 300g but never verified if that was with or without the parrots. What would u need for 3 aros? Would something like a 10x3x2 be enough or closer to 12x3x2?
this is a long term plan and the tank would be custom, built by me, so id rather know whats required. One thing i hadn't realized though is the massive amount of food even one of these beasts need. im leaning now towards something like 7 ft by 4 ft at a depth of 30 inches. 500 gallons which should give plenty of back and forth and enough turn room even if he or she grew to large for silver size and of course back down to one.