There are many deteriming factors in the growth of bichir mainly P.senegalus including quality of food,water temp. water quality and genetics.Extremely slow growth is not that uncommon anymore this could be due to farming and the gene pool which can lead to various genetic problems as slow growth and or stunted growth-Anne
Personaly I start all my bichirs off in a 10 gallon tank then move them to bigger tanks as they grow this allows me to monitor food intake,any possible disease problems and growth rate