need advice on stingrays

Yes, aros and rays make great tankmates.
As for size, depends on what species. The smallest i believe is a Potamotrygon scobina, which has a disk size of 12" adult. Also hystrix stay small as well. But these don't include tail length, only disk size.

I would recommend a minimum 30" wide tank for any rays (thats the very bare minimum, the wider the better). Same for the silver aro, once that guy hits 2-3 feet it'll appreciate a wide tank.
 
they will work well with an arowana (even both coming from the amazon river). Biggest problem is most of them grow quite large in diameter and require a very wide tank. The smallest of the Freshwater stingrays (P. Reticulatis and P. Hystrix) still grows to 12-14" in diameter. The largest (that I know off the top of my head...there is another larger) is the P. Motoro at a very wide 24-26".

My favorite are the P. Leopoldi stingrays. They NEED perfect water. Which means dont add them to a tank unless its been established for atleast 4 months and in good condition. Frequent water changes are NECESSARY as they like to have water that has ~5ppm of nitrates or less. I find myself doing a 25% water change ever 3 days. They prefer barebottomed or silica free sandy substrates (fine...anything rough will irritate their skin).

Favorite foods, blackworms (ESPECIALLY when young...my two still go nuts for them) earthworms, prawns, shrimp, and the ocassional mealworms.

Biggest thing to watch out for is buying them...if you buy from a LFS request to see it being fed...stingrays have amazing appetites and if they dont eat at the presence of food theres a problem. Also look for a sunken stomach (which you can see from above behind their eyes). Biggest problem with buying stingrays is the fact that a lot of them are imported and either die during or shortly after shipment. They are delicate fish so they arent the best at coping with shipment/movement. If you are going to get one make sure whoever you get them from is reputable and that you know what you are getting. Most LFSs mistag/ID the fish wrong (more often you endup with the name Teaup Stingray) and tell you they only get to be 12" when in reality the type they are selling are the motoro stingrays.

Trust me this is one fish you should DEFINATELY do research before buying. They require different handling and food than most other fish. Amazing fish they are but I wouldnt purchase one unless your willing to put the time and energy needed for them. but yes RESEARCH RESEARCH RESEARCH...best thing I could tell you.

Oh, also they do have stingers...and although Its near impossible to get stung (youd have to be paying no attention) but there is that chance. Ive almost been stung before. They are gentle though...I handfeed and even "pet" mine and they love it.

Goodluck in whatever you decide but they do require alot of space (id say MINIMUM width of twice their diameter) and energy to maintain their tank.

Sean

EDIT: erm...you beat me by like 20 seconds Spartan.
 
since the first link did not mention it...the fish are EASY to sex. Males have claspers on their back fins (the small fins easily seen on their underside at the base of their tails) females do not.
 
Thanks guys information verry helpful. one more question any good websites to aquire one? the lfs around here consist of petco,petsmart and two other shops neither I trust would rather go somewhere I don't know I'm going to get burned than getting burned knowing better!
 
ummm I can find one tonight (after work) because I found a couple and used one for my leopoldi. HOWEVER keep in mind that you will spend atleast over 100 dollars for one...my leopoldi worked out to be about 225. They arent cheap.
 
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