Introduction

[Tanks a 1ot]

I have a 120L tank which has been set up for a while but i'm still pretty ignorant to fish keeping so forgive all the questions. I currently have One blackmoor/oranda (can someone tell me the difference? Is it bad to keep one on its own?) 5 platies - 2males, 2females and one baby (is there a name for a fishes young and how do you tell the diffence between male and female?) I think i should get more female platies but how many and should i introdcuce them all at once? Obviously the females are getting a little harassed at the moment - should i seperate a male into another tank for the time being?
I've always wanted to keep a plec but everytime i get one it goes missing. any tips here? I think one of my platies is pregnant. should i put her it in a seperate tank and when should i do this?

[emeraldking]

Hi there and welcome...

One blackmoor or oranda will be fine. Sure, a friend extra would be nice but believe me they'll do just fine on their own.
It won't harm to introduce more platies at once. Most platies are quite hardy. The most obvious difference between an adult female and male is that the anal fin of the male has transformed into a gonopodium.
You can put the pregnant female (if she's almost due) seperate from the others. But you can also leave her in the tank. If there are sufficient hiding places for the fry, sufficient will survive. And not all platies will chase their offspring. Overhere, most of them leave them alone...

So, what happens all the time that every plec of yours seems to dissappear?