It would probably do. If you could find something with a bit more nitrogen (up to about 20% nitrogen) it would be better, but 12% nitrogen is fine. Nitrogen encourages leaf growth. If you use aquarium water (as suggested by Flushable Pets) will add a bit of nitrogen to the soil too.
The main thing I am concerned about is the heavy metals like manganese EDTA. I checked the website on the container and it didn't work, so I would find out what EDTA is and if it's safe for people.
This is the fertiliser I use. I has a bit more nitrogen but the phosphorus and potassium are similar. The trace elements are a little different but most of the nutrients plants require are nitrogen, phosphorus and potassium.
Yates 1.8kg Thrive All Purpose Soluble Plant Food
www.yates.com.au
As mentioned above, nitrogen encourages leaf and stem growth. Phosphorus encourages root development and helps thicken the cell walls. Potassium encourages flowers and fruits and also helps the overall health of the plant.
If you are growing lawns you have more nitrogen. If growing root vegetables like carrots, potatoes and onions, you have a bit more phosphorus. If you are growing fruit or flowers, you have a bit more potassium.
---------------------
Don't grow herbs in hydroponic systems because the plants don't like wet feet (water logged roots).
---------------------
Aquarium dechlorinators are fine for terrestrial plants and are not toxic for the rabbit. Metronidazole and other anti-biotics will get into the potting mix and the plants and can change the DNA of the bacteria in the soil and make them drug resistant.
Malachite Green, Formaldehyde and other toxic chemicals used in standard fish medications will also get into the plant and this is not good for anything eating the plant or its fruit.