Nice catch! Thank goodnes you could save it! Poly's aren't too picky for food at least 
As for the colour... I heavily doubt that it's a platinum. Polypterus colours vary greatly depending on substrate, health and age. My wild sen for example, was a very off pale green when I got him. He now sits around as a nice mottled olive with a tan belly.
Honestly I would hold onto this fish, a breeding age female senegal is pretty uncommon. I'd try and find a male and let them get busy
As for the colour... I heavily doubt that it's a platinum. Polypterus colours vary greatly depending on substrate, health and age. My wild sen for example, was a very off pale green when I got him. He now sits around as a nice mottled olive with a tan belly.
Honestly I would hold onto this fish, a breeding age female senegal is pretty uncommon. I'd try and find a male and let them get busy