Fish symbolise power, prosperity and wealth, and dead fish symbolise the loss of these things.

The idea of a pond with beautiful fish that has an opening with some dead fish seems to me, to symbolise a dark spot or stain on your wealth/power/prosperity. The idea that you have to "fish out" or fix the problem also plays into this....do you have mounting debts that need to be paid? Are you worried about stopping work and the loss of your income? Do you feel responsible for a financial crisis or hardship?

Just ideas to help you nut out the meaning.