In all honesty, I grew out my aro and two retic rays in a tank smaller then a 125. Have a very good filtration system and be anal about testing your water as well as changes and you would be fine with the rays for a while (retic or hystrix only) if purchased as a pup. If you plan to upgrade your tank for sure you could get a year or so out of your 125, keep a close eye on ammonia as rays create alot of it. It's a passion in the *** keeping rays in a smaller tank as a grow out but it can be done if you put in the work. Good luck!
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