Originally Posted by tommaso889
soo heres the my plan as my plec and algae eater are still able to fit in the tank i shall keep them (untill they grow out of it ) and then possibly getting a bigger tank a swapping them at the pet shop. as for my gourami i have been thinking of getting rid of them for a while as they are get aggressive towards eachother and other fish but then i need to decide what to replace them with :)
This is an example of why potentially-large fish should not be kept in small tanks at any time except as a temporary measure.
Keeping such fish in too small a tank until they "grow out of it" is not responsible. I am sorry to sound harsh, but the fact is that fish are living creatures for which the aquarist takes on the responsibility of providing what they need to be healthy. And as fish grow all their lives and continue to develop, they suffer internal problems from too small a space at the beginning. It is more than just the physical area of the tank. The damage being done to the fish in your tank now may not be outwardly noticeable, but it is going to mean health problems and likely early death.
The algae eater will grow to 6+ inches and become quite aggressive, plus they don't eat algae when they mature (assuming as earlier this is the common algae eater and not the Siamese--which also gets large but at least eats algae).
The pleco if a common one will be 12-18 inches and needs space now to grow and develop properly. Fish that are in too small an environment develop internal organ issues (called stunting), frequently become aggressive, and contract diseases they would otherwise fend off because of their weakened immune system from the stress.
Blue Gourami attain 6 inches, often 4-5 in aquaria, and need at least a 33g (3-foot) tank for a pair. Their aggression is normal, but will be intensified in too small a space (a 15g) and this again weakens the fish and causes problems for everyone in the tank, as you have witnessed.
The redtail shark needs more space, enough said.
The corydoras are shoaling fish that have a social structure within their group and need companions to be healthy. Three is a minimum number, 5-6 would be better. But first you need to decide what sort of aquarium you want before adding more fish that may not work.
Which brings me to the puffers--what type are they? Some require brackish water, some don't. They are not "community" fish in that they are pretty much a species aquarium fish, with the invertebrates another member mentioned.