From Paddy60's duplicate thread (which he has now removed
)
.....just done a 75%water change to reduce nitrate in case this level is slowing the cycle.
Is the ammonia reading still at 0.25 after the 75% water change? If it is, since there is zero nitrite I would suggest the cycle is finished. Ammonia can be difficult to distinguish between zero and 0.25.
To be certain, you could use
this ammonia calculator. It will tell you how much of your total ammonia reading (ie the tester result) is in the toxic form. In the calculator, set salinity to zero and enter the rest of the data from your tank's results. Click calculate and look at the lower of the two boxes, NH3 concentration. If that is 0.02 or less, the cycle has finished.
Since pH is one of the things you need to enter in the calculator, you'll also find out if you've had a pH crash as Andy suggests. This does happen, I speak from experience
Edit -
You posted the pH as I was typing. I've entered ammonia 0.25 and pH 8.0 in the calculator together with a temp of 25 deg C. The result is 0.0113 which is below the 0.02 safety limit. Even if the temp is as high as 30 deg C for cycling, the result is still below 0.02.
I'd say the cycle has finished. I know you've just done a big water change but another one about 25 to 30% should get rid of a lot of nitrate, then you can go fish shopping. Try to get nitrate down to tap water level.