Too many fish??

Question
I wonder if you can help me? We have just acquired our friends aquarium (they are moving abroad) the aquarium is 80cm long by 30cm wide amd 40cm high. We have counted the fish in there and there are 30, is this too many? I am not sure of all the species but there are two sharks in there 1 big 1 small, 3 small otto cinclus??(suckers)1 large suckerfish (stays in his cave all day! 1 angel fish 1 gourami, 2 tiger barbs, 2 clown fish, 2 tetras a cichlid (i think, large with beatiful blue and orange markings)2 danios and 2 beacon fish 2 tiny eels, 1 glass fish and 3 med size browny bronze fish which i dont know their species and a couple of other small ones which I am not sure about. They have been at my friends for about two years and have had no problems we have had them for just over two weeks we only lost one clown fish presumably due to the stress of the car journey. A couple of people who have come round (but not fish experts) have said that it looks a bit full so hence why I am asking the question!!!
Look forward to hearing from you, and I hope you make sense of my ramblings!!!
Thanks Nic

Answer
Hi Nicola,
I think your aquarium is roughly about 25gallons. And I agree with the other people who have come around that your aquarium is quite full. It would be good if you could thin out the population. Either move some of the fish to another aquarium or a lot of times you can get lucky with petstores who are willing to take in unwanted fish.
Its kind of hard to know what to advise about your tank since we aren't sure of the exact species living in it. It would be great to know that.

Since the tank is overcrowded, it would be best to try to divide the fish up in another aquarium. But for now frequent large water changes would be best to help keep the fish healthy and hopefully thriving until you can kind of help the crowded conditions. Something like 50% twice a week would be best.

Best of luck and I hope this helps!!!!!
Karen~