Help, novice -Rehoming tropical fish tomorrow

[SpottedTiger]

Hi, I'm completely new to fish keeping. My daughter has asked for fish and I've been researching and was all set to set her up with some Danios this week, then today my husbands friend offered to give us their tropical aquarium complete with fish. They have an angel fish and a red tailed shark, they've told him the heaters been broken for some time and that the tank needs cleaning.

So my main questions are:

The fish have been living without a heater for some time, will the fish have acclimatised to cooler temperatures, if we replace the heater could this harm them. I've read that temperature changes need to be gradual. How's the best way to do this.

My husbands thinking we should replace the substrate as it's very dirty in the tank (I've not seen it recently) but I've read that the bacteria that balance the nitrates live in substrate, should we keep it particularly if we are changing a lot of the water when moving the tank (also read to take as much of the original water with us as possible)

Thanks

Welcome to fishkeeping!

The heater - yes they will happier with one. A good heater will gradually raise the temperature and they will be happier, healthier and more active. They don't acclimatise to the cooler temps but have probably been benefitting from a centrally heated ambient room temperature. My heater broke in my 200L, I only really noticed as all my Rainbowfish were all clustered together looking miserable and cold, new heater in and they're happy again swimming all over the shop!

With the substrate, don't rush to replace but a good gravel vac should improve it.

The most important bit to keep wet and get running asap is the filter and filter media - that's where the majority of the good bacteria live (not in the water column). Treat the filter media as another living creature - it needs to stay wet, it needs setting up and plugging back in ASAP. And remember to dechlorinate any water with Tap Safe, as chlorine/chloramine will kill your filter bacteria.

Do you know what size the tank is?

Hi bunnygeek,

Thanks for the response. We successfully moved the tank, it turned into a rescue mission, the fish are only in a 30L tank, which was less than half full and so green you couldn't see the fish, the filter had run dry and the heater only wasn't working because the water level was so low . We ended up changing the gravel and replacing the filter cartridge, but kept a number if the pretty filthy ornaments hoping to bring some bacteria with us. I've been testing the water daily and all good so far. I'm aware the tank is far too small for these fish, so we will be upgrading as soon as we can afford to. The fish have lived in the current tank for 4 years, so I'm thinking a few more weeks won't be the end of the world.

The angel fish was completely black when we got it, but appears to be developing silver stripes, so I'm hoping that means it's happier. The red tailed shark has become very active the last few days and started to bully the angel fish, which the previous owners tell us is the normal dynamic in the tank. I'm hoping moving to a larger tank will help. I've noticed that sharky seems to have been searching for food and nibbling the algae on the ornaments non stop today and am wondering if we are feeding enough, but aware that over feeding is not good.

My adult ds had a great set up and some beautiful fish.
Until he got a smart meter and also watched that spinning round..

Sadly they had to go.
Which was a true shame as his mh vastly improved...

Unless you have extremely large set ups, or a large number of tanks, they really don’t use that much power @Chocolatecomaday. Smart Meters are a con. An average fish tank will use less power than a washing machine or fridge.

@SpottedTiger that’s great news the fish are recovering. So sad they’ve been in such a tiny tank. They really need at least 150 litres - look second hand, just make sure the seals are good before you set up.

@bunnygeek, Thanks, yes that's the sort of size I'm after, scouring marketplace at the moment.