ESP8266 socket - transmit bytewise

I'm trying to read data from an Arduino UNO and send them via Serial to a ESP8266 in order to transmit them to my pc in real time.

/*EACH FLOAT*/
           
            byte byteFloat[sizeof(float)];
            //memcpy(byteFloat,(unsigned char*) Serial.read(), sizeof(float));*/
            data = Serial.readBytes(byteFloat,sizeof(float));
              /*4 BYTES FOR EACH FLOAT*/
              for(j=0;j<4;j++){
                   client.print(byteFloat[j]); 
               }
          client.print("-");

The result is always 4 byte set as 0 , read via PuTTY it returns a wall of '0000-'
How can I make it work?
thx