the fish wastes are good for the plants but what you have to watch out for is the salt accumulation. Several of the chemicals used in fishtanks cause salt accumulation. For example chemicals that correct PH, de-chlorinator...etc. They fix the problem but almost always they increase the level of salts. On top of that, some people add salt even to freshwater aquariums because it actually helps the fish stay healthier.
I have the same problem with the pool water (and I don't use ALL the pool chemicals) but my kids pool is 1800 gallons and I hate wasting that much water, so it goes around my shade trees. The first time I did that, I killed a tree (I didn't balance the ph that time and I had just pruned it severely in the middle of the summer so it wasn't just the water)
I use bleach to chlorinate the pool. the chlorine is gone within a day here in the arizona sun so it isn't a real issue, but bleach is sodium hypochlorite. The chlorine evaporates, and the sodium stays. I've been entertaining the idea of trying the ion exchange method (same thing they use for water softeners) to treat the pool water before dumping it on plants. If I could exchange the sodium in the water for potasium, it seems to me like the plants would like that much better. anyway I think that's enough ranting.

Ranting?

Greendesert, that is great information..In fact, it was the water I use to give my plants from my fish tank that actually caused problems with my plants over time..

Thank you for that...

Mike

Greendesert thanks for great information, so if I stop using de-chlorinator and just leave the water out for 3-4 days, filling fishtank, 14 days i use that water , will cause any problems over time?

I don't think the fish wastes would cause any problems to your plants. They're mostly amonia and nitrates which the plants would love. If you run an aerator in the water for a few hours, the chlorine would dissipate even quicker. Also sunlight speeds that up. Now I just read up on this stuff and it also depends what your city uses to treat the tap water with. If they just use chlorine, it will dissipate fast. Some places add chloramine. That stuff is much more stable and will not dissipate so you would have to use dechlorinator to avoid hurting your fish.
The other thing is that you don't want to put chlorinated water in the tank if you have a biological filter in there, because the chlorinated water will kill microorganisms on the filter which are responsible from removing nitrates from the water. So dechlorinating the water before you add it to the tank would be the best thing.
Every kind of dechlorinator I know of, can cause sodium and other stuff buildup:
Sodium thiosulfate
Sodium hydroxymethanesulfonate,
Sodium hydroxymethane sulfinic acid

The good part is that I remember it didn't take much dechlorinator to treat the water, so the buildup may be fairly minimal, but still it depends on how much stuff is already in your tap water. Here, the water is already very hard and high in salts so adding more to that is not going to help.
So anyway, I don't know if the dechlorinator would cause problems for your plants, that would depend on levels already in your water, but if you add salt to the water on purpose, then I'd think twice before using that on plants, (although not all plants are equaly salt sensitive).
anyway, that's what I know, someone please correct me if something doesn't make sense.

I tend to feel that just because aquarium water has some nutrients is not a good indicator it's necessarily good for your plants. Here's why: We know it's not complete and that it doesn't contain nutrients in a ratio that's favorable for plants. That means that using fish emulsion alone as a nutrient source will definitely limit growth (Liebig's Law of the Minimum). To prevent growth from being limited due to nutritional deficiencies, you'll need to supply either a soluble fertilizer or organic soil amendments, with the former being an easier and more reliable way of delivering nutrients. So here the aquarium water user is - wondering what nutrients he's supplied and what nutrients are lacking. With no way of knowing, he reaches for his fertilizer and applies it according to directions. This should deliver a dose of all the nutrients necessary for growth in a favorable ratio (if it doesn't you used the wrong fertilizer). This application makes the nutrients in the soil solution derived from the aquarium water redundant. They actually serve no purpose, and in fact, unnecessarily raise the the level of EC/TDS higher than if they were not present, making it more difficult (though marginally) for the plant to take up water and the nutrients dissolved in water, so you would have been better off w/o it - with sticking to a fertilizer plan you KNOW provides all the necessary nutrients at a favorable concentration and in a favorable ratio to each other.

RG - your plant has obvious nutritional deficiencies. My guess, because of the interveinal chlorosis AND the cupping of the leaf margins is that it's short at least Mg, and very probably N and others. If you're willing to answer a few questions, I'm pretty sure we can narrow things down and get your tree back on track.

Al