Dinner in the 7th

20 euros at dinner including wine is a challenge for good French food in Paris, especially in the 7th. And I'm not sure what you mean by "small plates"?
The only place I have in mind within that range is the Café du Marché, on Rue Cler, but it's not big on seafood.
At lunch on weekdays, Café Constant is also close to that amount.
But increase your budget to 30-35 euros, and a whole range of options will open...

Metro makes any place in Paris next door. Use Michelin Bib restaurants to find a good buy.

If you find a place to have dinner that includes seafood, cheese and wine for 20 euro, please let us know. What about bread and coffee ...... included in the 20 euro?

I do not know of a place in the 7th where you can have a glass of wine, seafood, and cheese (even with small plates) for 20€ per person. You may be able to get two small plates and a glass of wine for that budget at L'Avant Comptoir wine bar in the 6th. Unless you have a very tiny appetite, 20€ will get you a large snack (not dinner) at L'Avant Comptoir. You would have to order carefully. For a bistro, I agree with Balso about the budget range that will get you options for dinner.

You guys are all correct. 20 E is a little tight. I save money traveling by having a glass of wine with nuts and cheese both before and after dinner at the hotel leaving only one plate necessary for dinner. But this is Paris not West Sonoma where I live. It will probably be 30 E.

I can usually eat for around 20E in the Rue Cler area but I'm vegan so not looking for cheese before or after. For vegan risotto (with a small green salad) and a glass of wine I'm pretty sure I paid exactly 20E at Cafe Roussillon at the corner of Rue Cler and Rue de Grenelle. I'm not fussy about wine - usually go for something in the range of 6E a glass. If I get a small coffee after it's usually 2E extra.

Have a wonderful time in Paris!

Le Roussillon is a good shout out, seconded!