You wouldn't ever be able to tell this, because carp fish do not get pregnant. Pregnancy implies carrying the young internally, which carp do not do.
Koi are a type of specially bred carp.
Danios are egg layers and can not get pregnant.
I would imagine that with some fish it would be nearly impossible to tell until they give birth. However, with a thin, transparent fish, you sometimes can see a dark spot in their belly!
it would not be happy if it does not eat that is normal it will loook desperate that's normal too
a catfish has whiskers and a carp doesn't.
Pregnant fish may appear rounder or have a swollen belly. You can tell if a fish is expecting offspring by observing its enlarged abdomen and possibly seeing small, developing eggs inside.
To talk; to speak; to prattle., To find fault; to cavil; to censure words or actions without reason or ill-naturedly; -- usually followed by at., To say; to tell., To find fault with; to censure., of Carp, A fresh-water herbivorous fish (Cyprinus carpio.). Several other species of Cyprinus, Catla, and Carassius are called carp. See Cruclan carp.
Goldfish of any type are all egg laying fish which means that they do not get pregnant
With a guppy you need to look at the gravid spot. This is a dark spot in the fish's belly. A large gravid spot indicates the fish is likely to be pregnant. You can tell how pregnant the fish is by how large the spot is. Sorry I have no experience with other species.
To determine if a fish is pregnant, look for signs such as a swollen abdomen, changes in behavior, and a darker gravid spot near the anal vent. Pregnant fish may also exhibit increased appetite and aggression.
Orandas, or any other type of goldfish are egg laying fish, so they do not get pregnant
Black moors are a variety of goldfish which are egg layers so they can't get pregnant.