Kosher fish

Lev 11:9 These shall ye eat of all that are in the waters: whatsoever hath fins and scales in the waters, in the seas, and in the rivers, them shall ye eat.
Lev 11:10 And all that have not fins and scales in the seas, and in the rivers, of all that move in the waters, and of any living thing which is in the waters, they shall be an abomination unto you:
Lev 11:11 They shall be even an abomination unto you; ye shall not eat of their flesh, but ye shall have their carcases in abomination.
Lev 11:12 Whatsoever hath no fins nor scales in the waters, that shall be an abomination unto you. 

The LORD had his reasons for prohibiting the eating of things without scales or fins. Some of these foods from the waters are popular foods, often quite expensive to buy.

The list for the Jews to not eat included shellfish, crabs, shrimp, catfish, lobster, mussels, eels, sharks, sturgeons, and swordfish, just to name a few. Science has shown that fish with scales and fins are equipped with a digestive system that prevents the absorption of poisons and toxins into their flesh from the waters they call home. Catfish are bottom feeders and shrimp and shellfish tend to absorb any toxins that are in the water. If you enjoy eating these, be careful where they come from. Areas with polluted waters are more likely to have toxins in the flesh of the creatures without scales and fins. A fish is kosher if it has scales and fins. Kosher fish include tuna, bass, flounder, grouper, perch, salmon, snapper, trout, herring, Tilapia and others with both scales and fins. a kosher food is a food that conforms to the Jewish dietary laws.

What about a Christian? Are these laws to be kept?

1Co 10:25 Whatsoever is sold in the shambles, that eat, asking no question for conscience sake:
1Co 10:26 For the earth is the Lord's, and the fulness thereof.

Rom 14:20 For meat destroy not the work of God. All things indeed are pure; but it is evil for that man who eateth with offence.
Rom 14:21 It is good neither to eat flesh, nor to drink wine, nor any thing whereby thy brother stumbleth, or is offended, or is made weak. 

Rom 14:22  Hast thou faith? have it to thyself before God. Happy is he that condemneth not himself in that thing which he alloweth. 

Rom 14:23  And he that doubteth is damned if he eat, because he eateth not of faith: for whatsoever is not of faith is sin. 

Basically we are free to eat anything if it is done by faith and does not offend a brother.