looks like they're setting it up for a turtle or something from the look of the gravel slope and the green tetra filter (same as the black but they call it the reptile filter). i still don't get the heater though. either way stock photos are always crap...lol. but yeah they definitely look well versed in keeping aquatic pets(psych...haven't used that since i was 10).
it might not only be fore fish... could be used for frogs, turtles or newts... where more grvael will be placed to one side which allows the animal to get out of the water