All right. My previous post was tongue-in-cheek; I'm used to working with pros, so I wasn't paying attention to the context of this discussion. Consider the first figure, regardless of the temperatures listed. This could be your aquarium: room temperature 70°F, aquarium temperature 70°F, everything in thermal equilibrium. To measure the temperature of your aquarium, you can immerse the 10 mm probe, good thing; but you can also not bother to install the probe inside, and pull a cable through the room: put your probe anywhere in the air of the room, it will tell you the temperature of the aquarium.

Look at what I wrote: "when the temperature difference exceeds about 10°C".
Professional cooks have to cool down very quickly (in special refrigerators) the food coming out of the oven, before putting it on hold at 40°F, for the future meal. In the professional context, the probe would not measure the right temperature, because at the place of the red circle, a thermal flow goes from the probe (hot) to the external cable (cold), and its copper conductors very good thermal conductors: thermal flow, so temperature difference, so the sensor is marred by a temperature shift (maybe 45°F) with respect to the food to be measured, because the copper electrical conductors carry this temperature to the core of the chip. It takes (at least) twice the length of the sleeve immersed in the mass to be measured, to reduce this offset.
Same thing in the other direction of temperature differences. In order to use the probes properly, I specify that they should have 20..30 cm of cable length in the cold environment.
33% of the users don't care,
33% install the probe flush to the inner wall (and come back to tell me that the probe gives false measurements),
33% will put about 15..20 cm of cable length in the cold room which is the minimum, that's why I say 30cm. If I had said 20cm, they would have put 10cm, which is not enough.
Technical work requires taking into account the psychological behavior of users...

Mais pour votre aquarium, vous avez raison, vous pouvez utiliser la sonde n'importe comment, elle donnera toujours une mesure plus ou moins approximative de la température de l'eau. Même hors de l'aquarium !