How do we plot nonlinear differential equations

Question

If this is not nonlinear I apologize, I'm still learning differential equations. I am attempting to make a stream plot of a predator-prey model of eccentric closed curves by using the following commands and then find the period of oscillation max min number of population etc. and when plotting the oscillatory plot they are out of phase. I also tried making the constants below arbitrary and then attempting to plot this just creates more issues

 deq1 = x'[t] == 0.01*7*x[t] - 0.0001*4*x[t]*y[t];
 deq2 = y'[t] == -0.01*8*y[t] + 0.0001*5*x[t]*y[t];
 StreamPlot[{deq1, deq2}, {x, -0.1, 600}, {y, -0.1, 600}]

I have successfully created a single ParametricPlot using to result in a single eccentric closed curve

  solution = NDSolve[{deq1, deq2, x[0] == 600, y[0] == 100}, {x[t], y[t]}, {t, 0, 500}]
  ParametricPlot[Evaluate[{x[t], y[t]} /. solution], {t, 0, 400}]

Answer 1

As explained in a comment, typing there the line

streamplot[{0.01*7*x - 0.0001*4*x*y,-0.01*8*y + 0.0001*5*x*y},{x, -0.1, 600}, {y, -0.1, 600}]

produces

Lazy people would rather type the line

streamplot[{7x - 4xy,-8y + 5xy},{x, 0, 6}, {y, 0, 6}]

which, for good reasons, produces the same diagram, only rescaled: