Many fish can handle around 1000 TDS or even higher just fine (you just don't want to move them to water with drastically different TDS without acclimation. So actually you don't want to quickly lower the TDS on your cichlid tank just because you freaked out about the measurement. Do it slowly, if at all. If high nitrates are leading to the high TDS measurement (which they can), then do water changes to lower the nitrates specifically).
Those numbers are pretty normal for people that have hard high alkalinity tap water.
The main reason we worry about TDS is with acclimation because a quick change in it can cause osmotic stress on your fish.
As far as long term housing in water with a specific TDS measurement, this is mostly a worry when trying to spawn because eggs and fry may be sensitive to a certain level. Some species, even as adults, may be more sensitive to high TDS levels, so you need to take the specific species into account when considering what levels are appropriate. You can't really generalize for all fish. If you're fish are doing fine and you've never had problems I actually would not worry too much about it.
TDS itself is a measure of various components (metals, salts, nitrates, etc.), so unless you have something specifically harmful to your fish leading to high TDS that measurement itself means nothing to you as far as long term housing unless it's on the extreme high end (and yours is not necessarily).
One thing the meter may be helpful for, is using it to measure your tap water when you do water changes. The TDS can fluctuate and if you get an extremely different reading than in tank you may want to do several smaller water changes instead of one large one, as it would be less stressful to your fish.
Or if you get new fish that are in water with an extremely different measurement you may want to give them a longer acclimation time.
