If it seems that the fish is attempting to swim upwards your fish has a swim bladder problem. Your fish will die from this eventually. Pet stores may well attempt to sell you something to fix this. IMO you would be wasting your money. I would destroy/euthanase the fish.
yes, crabs can swim left, right, upwards and downwards
You probably scared it
no some swim upwards however they cant swim backwards but.. they do like to try. Whales have huge dongs.
No, the density is too low to provide the upwards force needed.
To get to the other side! Where did you get the back and forth kind? Mine only swim to and fro. In semi-seriousness, angelfish in their natural habitat have freedom of movement and exercise that. In an aquarium, back and forth is the only way to go. If you will allow a moment of anthropomorphism, they're probably looking for the way out.
with there mouth open
because its probably sick and need to see a vet... if this continues notify your vetit probably has some kind of diseaseMost likely a swim bladder disease
no. EDIT: Incorrect. Fishyfisher82 has a two year old veil angelfish in a 36gal tank (and all the size that implies) with a trio of glass cats who have been coexisting for well over a year. So long as the fish can swim quickly and are not too tiny, and you only have ONE angelfish, you're fine. Angelfish will most likely eat guppies, though.
The penguins swim fast with their beaks pointing foreward for hours.
yay. whale sharks dont have teeth, they only eat small sea animals. and its mouth is big enough, probz youll be able to swim back out if your not runnin out of oxygen.
probally fresh because no salt in mouth or eyes addition: it is easier to float/swim in seawater since seawater is denser than fresh water.
Larvae swim either through propulsion with their mouth brushes, or by jerky movements of their entire bodies, giving them the common name of "wigglers" or "wrigglers".