territorial chocolate oranda

Question
I have a 26 gallon, 2 1/2  month old tank.I Test the water and do about 25% water change weekly. I first bought 2 chocolate Orandas, one a bit smaller than the other and after 3 weeks I lost the smaller one and have since been trying to learn all I could about feeding and caring for them. I now feed "Smooch" the larger, only child in the tank, alternating of flake,Hikari floating pellets, a green pea and sometime a bit of orange or zugini slice. I have been waiting for the fish store to get in some more orandas and finally after 3 weeks they did, but a lot smaller, Smooch is about 2 1/2 x 5 inches. Beings they were so much smaller I thought the  tank would maybe be okay for 2. Anyway , long story short, I brought the new babies home and Smooch did not like it. Chased those poor fish all over the tank, pushing them all around, like Get OUT!I called the fish store and she said to feed them and turn out the light and watch. Well..Smooch was not interested in that food, he just wanted those fish out. So Got up the poor things and took them back to the store and put my order in for one a whole lot bigger. Now do you think it will work out if they get me one about the same six? and by the way Smooch is black with an orange head and black markings on the face, do you know what kind of chocolate Oranda "he"? would be?
Thank you for any help? Oh, one other question..I see horror stories about choking on small gravel , should I slowly change this gravel for larger?
Thank you much for any help,
Glenda


Answer
It is actually mating season now, so its possible the babies where female and he's a hefty male thats ready to make some babies, basically the male will chase and chase the female until she is soooo tired he an guide her to a plant or something and headbutt her abdomen until she realeases her eggs.

For the gravel you change change it all together just take him out and rinse the new gravel thouroghly.

Try buying one his size, maybe a bit bigger if you can, but i think it may be a mating issue, if he carries on, i guess he'll have to live alone.