I agree. I have a few juveniles (2"-2 1/2") in a 30G, but within 3 months I'll be splitting the 5 between 2 30Gs, and within a year I'll be moving them all to a >120G. Severum get quite large. Some say up to 12 inches long (which means 6-10 inches high) but then generally only reach about 9 inches. At that length a sev would be very cramped in a 25G. Unless you plan on upgrading your tank, or not keeping your sev very long, severum aren't for you.