archers are brackish...you could do just about anything that wont fit in the aro's mouth...i have a 13" with 1-florida gar,8-redtail tinfoils,3-bala sharks,1-ropefish,1-goldnugget pleco,1-baby redtail cat(for now) and 2-black ghost knifes...my tank is 72"x24"x24". any of these will work for tankmates. done worry about drop eye most silvers get it... it's bad genetics from farms to much inbreeding..imo. it also happens from tramma...thats when mine got it( it jumpped out). i have black sand for bottom..no problem! i have read alot of things about aro's most say sand is prefurred. they live in the backwaters of the amazon river the bottom is sand/dettris material. mine eats everthing i put in bite size. from rotissary chicken to a bit of baby redtail cat (its ok though). good luck with the aro!!