Theres are factors that play into growth rate - Sex M or F, Alpha status in the tank, Alpha status within the species(genetics) , over all health, and varients within species - but with all things being equal meaning 3 Dom. Males within' the 1st year - Texas first to hit the 6" mark than growth slows greatly, Oscar first to hit the 10+" mark and very robust, Jag steady growth rate of 1/2" to 3/4" per month will probably be around 8-10" after end of 1st year.