Beta not looking very good..:o(

Question
Hi Jaymie,
I have a Beta, George Harrison, in a 4.5 litre tank with a small filter and light.  It has gravel, plastic plants to hide behind and the water is currently about 78degrees.  I had an algae problem for a few weeks, and was recommended to use Algaefix to get rid of the green water and algae buildup which continued to grow even after water changes.  I also bought him a tankmate, Ringo...a little catfish. Since adding the algaefix, George has been lethargic and hiding between the filter tube and tank wall.  He is turning grey and doesn't move much. :o(  I changed 50% of his water using his beta water treatment and stressguard, but he is still looking miserable and not eating.  Please help...
Thanks...Meg

Answer
Meg,
The biggest problem I see is the tank size. It is not big enough for one fish let alone two. The absolute smallest tank for one Betta is 10 liters, where 19 liters is better. Also, 78 degrees is too cold for him. He needs to be between 80 and 82 degrees. With a tank that small, it is impossible ti keep the water even 78 degrees. There are no heaters that will keep that tank warm enough. You now have two fish in a tank that is way too small. The problem with the Betta now is that it is very hard to treat a tank that small with the right amount of anything. Chances are you put too much in his tank. I would change out all of his water, make sure the heater is set at 82 degrees to help him get better. You might have to change his water a couple of times until all the Algaefix is gone. I never recommend adding anything to a tank that is that small.