Financial Catfishing
Criminal Law
Financial catfishing is where a person uses a false identity to make money for themselves or to cause a financial loss for someone else (the victim).
Whilst there is no one individual crime of catfishing where money is involved as part of a catfishing scheme this may constitute the crime of fraud by false representation, which is a crime under Section 2 of the Fraud Act 2006. This offence may be caused in one of two ways. The first is where someone f falsely represents who they are in such a manner to give themselves a financial gain. The other is where a person falsely represents who they are which causes the victim to suffer a financial loss (even if the perpetrator was not the one who received a financial benefit). Thus if you gave money to someone who was a catfisher it is possible this may be an offence under Section 2 of the Fraud Act 2006.
However, whilst this may be an offence in theory, there has not been a case where a person who caused financial harm by catfishing has been prosecuted under this act. Whilst this doesn't mean that the act does not criminalise such behaviour this may show hesitancy or difficulty from/for prosecutors to bring these types of cases
Civil Law
In regards to fraud and other financial exploitations from catfishing your best bet will always be criminal law, but a tort exists at common law which is relevant to these sorts of situations. The tort of deceit is the most relevant. It requires there on the behalf of the catfisher to make a representation dishonestly which you relied on to your detriment in some way.
The representation that is made dishonestly must be a factual information, meaning not opinion or speculation. As for dishonesty it is defined as making the representation which is false knowingly, without belief in its truth, or recklessly careless as to its truth. For relying on the representation it is not requisite that it causes your reliance but that it is a real and substantial part of your decision to rely on said representation.
If you are interested in more information the best cases to look at in this regard are Derry v Peak and Dadourian v Simms.