lol i know I'm gonna get flamed by this since mfk is all about tank size but I think that combo you suggested could possibly work but just not for long term. And as long as you dont powerfeed like many of us do(maybe say once a day or every other day) you could keep them for at least a year. Be aware that many people love to exaggerate growth rates and most like to estimate size without use of measuring tape, for example, one guy estimated his arowana to be 24-25 inches, but when he actually measured it, it turned out to be 19 inches. Also, as suggested, you could keepp some freshwater barracudas for long term, and they are pretty interesting. If you do not plan to keep for long term then you should probably look for homes that will readily accept them after a year or so. Good luck with the project!